Can my recent repair have caused my camshaft to freeze?

There is the [possibility that the timing belt/chain was installed a tooth off where it should have been. The power steering will make noise until bled but that should not take long. You might have been hearing the camshaft bearings spinning if they were damaged.
The only way to definiteavly say if this happend is to see if the valves hit the piston which would damage the valves and the fact that the camashaft may have been off time would cause issues as well. It takes a good bit of contamination to stop the oil flow to the camshaft and a ceazed camshaft is rare. I do not know the specific vehicle but I would think that the oil feed line, which is an actual seperate oil line to bring oil to the top end, may have been damaged and pinched off somehow during repair.
My biggest question is that the camshaft ceazing would have, and I am sure if you look at the oil now you will see this, large specs of metail in the engine oil and it is something that I think would have been apparent to most techs.
However, it is really tough to place blame but the bottom line is that they worked on that part of the motor which was operating fine until they worked on it and then it failed very quickly. If there was an issue before you brought it to them with the camshaft oil feed, you would have seen metal in the oil, not always easy to see as it can be small specs when it is failing and has not spun a bearing yet, but you would have heard some noise and the cmashaft would have more than likely failed slowly and made noise before it just ceazed. I find it suspect but it will be difficult to lay blame on them as there are so many variables. Your best bet is to take it to another shop. If the mileage is not a type and really is 14500, you don't need a timing belt for 60,000 miles and timing chains last a while longer.
If it were worn this prematurely the tech should have known that something was straining the chain. If this is the case I can see the camshaft being in a failing state and the tech just missed it, but it should have been looked into if it was worn out prematurely.
I know this is a lot of information that does and does not help, but it is hard to truly say that they are at fault even if I could see the engine. It would have had to have been something I would have needed to see before the repair.
I do think you might look into getting a used engine as there will be some damage from the metal that came off the camshaft bearings when it failed. If there is an oil feed issue you don't want to be unsure of it's cause and fix the motor and have it happen again.
Which brings me to the best questions you can ask;
Was the timing belt prematurly worn or any components?
Did that not lead you to think there was another issue?
Why is the camshaft not getting oil?
If they can't tell you why it is not getting oil, you need to stop and evaluate your next move. You at least need to go to another repair facility that is more reputable. If you need help finding one the search engine on this site will help you find one near you. Just look on the page for ads that come up after you search the term, transmission rebuild" or something like that. You will find several ads for repair shops that are reputable and the search engine will attempt to get the ones nearest you.

It is too late to get Toyota to help you as too much time has passed. Did you get the recall fixed when it was sent to you?
The cam seal would not have caused this. The fact that you have a lot of sludgfe in the motor could be a reason. But this is from lack of changing the oil every 3000 -6000 miles. If you changed your oil regularly, and fuel system cleaner helps, it should not be enough to cause that type of issue unless you drivve in really dirty or stop and go driving. It is an older engine though and things do happen. Sometimes when services are performed sludge and things like it get jared loose and cause problems. It is very possible that this happened.
Unfortunately in the end there is no way to lay blame on anyone. The burden of proof is not on anyone to say yes or no that any party is responsible.
You can get a used engine for your car for under $1000. You can even get what is called a, "Japanese Domestic Market" JDM engine and it wil have around 30,000 miles on it. This is because there is a law in Japan that requires a new engine at 30,000 miles. So, there are tons of engines for sale with this mileage. You can find a dealer pretty easily on the internet to get one if you use JDM engine as a search term. You will be able to get it shipped for the $1000 as well and if the dealer wants more you can find someone that will sell you that engine for around that price if not cheaper. You may even find an engine and transmission combination for around that price and get a nearly new transmission as well. It is essentially a new engine but I reccomend replacing the seals, water pump and timing belt before installing it. Some dealers require this if they have a warranty.

The camshaft bearing would need to be replaced. If one of the camshaft bearings was damaged, I would imagine that all of them suffered some kind of damage. Bearings come in sets most of the time anyway and are easily installed with a special driver and a hammer. If there is sludge in the top end there is bound to be sludge elsewhaer in the motor. I would remove the oil pan and have it cleaned out and put back. After all of this is done, you should run some quality oil in it and change it early. So, get some good oil and change it at 1500 miles and see how dirty it looks.
You might also run some engine or fuel system cleaner. Some good fuel system cleaners are SEA FOAM and BG44K, you will have to go to a car dealership to get that. Run a can or two in the tank as directed and then chagne the oil after running two cans as it will loosen sludge and you want to get it out of there.