Oh, I hope not. The saddleback is kind of skittish, so if it looks to be causing trouble, I just have to approach the tank! I have also never seen it divebomb the mouth. It tends to either lay in the anemone at night (during the day he swims around the rockwork) or he will hide behind it and stick his out through the folds.
I did add phytoplankton to the tank last night and then the mouth was open really wide (well really not the mouth, more the protruding stomach). Actually, now that I watch him for a few minutes, that is exactly what he does. The anemone will expand his stomach out through his mouth (just 2 bubbles) and then touch the stomach with each of his folds/tentacles. Perhaps, this is some form of filter feeding as he will not eat the silverside (at least just yet).