Every fish is different. Not all filefish will eat aiptasia, BTA, or soft corals. And a well-fed filefish will go after all three of those at a much lower rate.
That said, softies and anemones are always going to be at risk with any filefish in the tank. I don't know how rhino filefish compare to bristletails, but I've had 3 of those over the years. Of those: 2 ate aiptasia, one ate zoas, one picked at fleshy LPS like acans, and one ate only prepared foods (pellets/flakes). My current filefish is the one that eats aiptasia and picks at LPS, but thus far he hasn't picked at any of the LPS enough to kill them and they actually all seem to be recovering. He has eliminated large aiptasia, with only smaller ones that he doesn't see or can't get at left in the tank.
If you like your BTA, I wouldn't risk it with a filefish.
