We haven't been charged when my son didn't eat...and several trips that meants we were left with several extra child's
DDP meals which we were able to use as adults at Sci-Fi. Disney has been more than accomodating for us!
We have brought McDonalds to Teppan Edo with no problem.
We weren't charged when our son fell asleep at Chef Mickeys, and when he didn't eat at Garden Grill (he was freaked out because we were moving) not only did they not charge us, they let us take his food with us anyway!
We weren't charged at Akershus when he didn't eat anything they had (all unacceptable and not on his self-limited diet list.)
At Hollywood and Vine they don't serve french fries and there was nothing there he would eat. The waiter went next door to Sci-Fi and brought us a big plate of chicken and fries for him...he got a big tip LOL
If you have any other restaurants in mind let me know and I'll tell you if we have been there, because we have done most, and have had to deal with diet issues at each one. Overall we have found all of the Disney restaurants to be more than accomodating. The only place we have been told he would be charged no matter what was at the shows (Mickeys Backyard BBQ, etc) Officially though they may say you will be charged.
Good Luck!!