I think it's completely ridiculous. The whole claims of "ableist" are uncalled for as Derpy is not the first silly looking, clumsy acting character to grace cartoons. The argument of the deep voice isn't really strong because it was a mistake on the VA's part since she didn't realize Derpy was a mare.

I personally think that what's more ableist are the people attacking Derpy. The people that are suppose to be being defended that I've either talked to or heard speak up actually love Derpy and think the people claiming ableist are off base and actually more offensive. Basically, many of Derpy's attackers are more offensive and ableist because they are suggesting that the people they're "defending" can't do so themselves (and maybe even that they like Derpy because "they don't know better". Which is further insulting.)

Last I heard from the official response is that Derpy is safe. No explanation about the missing iTunes episodes though. (Hearts and Hooves has been pulled after it was accidentally released early and not put back up as of yet, suggesting maybe reposting after pulling is an ordeal?)