If it were not safe, the whole grabbing/washing/seasoning/baking routine would have been a waste of time and effort, wouldn't it?

long as you didn't have drain cleaner or some other horrible caustic material in the disposal, we doubt there was anything in there that couldn't be safely washed off.

Some people have drain guards to keep their precious silverware from sliding unnoticed into the disposal. Your needs are a little different, but perhaps you would like to put one to use, as well.

And we're sure you grabbed the chicken breast from the disposal with a pair of tongs, right? There is nothing in the world for which it is worth putting your hand in a garbage disposal, at least not unless you've turned off the circuit breaker.