I am guessing she is hearing?
Regardless for extra curricular activities and such and not provide him with a Terp for P.E. of after school functions I don't think it is a bad thing. In fact, I think it is good to expose him to more independent learning with out a Terp. Only reason is because you can't pay for a Terp to follow you around all your life. I think everyone regardless being deaf, blind, etc.. should learn to cope with the everyday problems of being around people. Not sure if I make complete sense or not but, I tried.
I mean does she realize that deafness doesn't prevent her son from doing anything but, hear? I mean I do fine, yeah I wear hearing aids and lost my hearing later in life and learning to read lips has always been an ongoing struggle for myself but, I cope with it. I only have about 40% understand of speech on with my hearing aid.
This is a child. He is being socialized through extra curricular activities. One of the major rasons that deaf students in the mainstream experience problems with social skills development is because they don't have the access they need to develop those skills.