This makes no sense as an excuse. I 100% guarantee that people would be willing to subtitle the videos for them for free if they would make them publicly available.

I would gladly spend a couple hours subtitling a lecture video so that the whole world (including deaf people) could watch it.

It might benefit current deaf students enrolled there too.

It just seems incredibly petty to stop publishing the videos over something like that.

Do they really think it would be that hard to subtitle the videos? Or are they just morally opposed to being required to provide accessibility in general?