The problem with C as a language for learning is that the error messages are not very specific or descriptive and often you need extra context to understand what is happening. Messing up memory management can result in inconsistent gremlin-like behavior from your programs, it can get very tricky. I had a pretty difficult time when I got to classes that taught C compared to other languages, but the main thing was just that I needed someone to look over my work and explain things to me because unlike with other languages, the self-service ways of figuring it out were much more difficult and it's easier to get stuck with no idea what to look into next. I ended up begging people online for help with understanding what was going wrong with my programs to supplement the limited amount of time the professor and TAs were available, really grateful to those guys as I probably would have failed it otherwise.

Anyway I would just say that if you do really want to go with C, I think you should be willing to put in more time to explain things to students one on one because many of them may need it.

If you teach them C, they will then be able to digest JS in an afternoon...

Good call. At this point the jankyness of js doesn't pose a problem and the ones that get enticed will learn about type safety, classes etc down the line.