Am I Overstepping?

A good friend of mine is a language wiz. He speaks like fifteen different languages. However by his sophomore in college he completely lost his hearing (due to genetics). He knew it was a possibility but since he was in his twenties without much issue he wasn't prepared for it. His hearing loss started to show in that he wasn't catching everything people were saying but he tried to compensate and often times he missed what people were saying so he would answer incorrectly. Professors began to treat him beyond poorly, making fun of him, telling him to quit, put him down etc even though he was a straight A student so they knew he was good.

Now we're out of college and he refuses to speak any language other than his native english like his confidence is completely gone.

Would I be overstepping as his friend if I suggest he learn sign languages in the different languages that he knew? Like french sign language (since he spoke french), chinese sign language (since he spoke mandarin) etc. I just don't want him to feel I'm being insensitive. He was really good at languages and I want him to know that he still has options.