BTAs are very hardy and can usually survive a trip into the power given the water condition is good. I would leave everything as is.
If the Vortech is a constant issue for the anemones, you can get a cover or make your own out of foam pad. This will reduce the pump flow of course but will protect your critter.
One other thing is that, if you don't have rocks touch the glass, it makes it harder for the anemone to walk onto the glass and into the pump. Non-sand dwelling anemones hate being on sand. If it's healthy and water condition is good, it shouldn't detach from the rock. It may walk around on the rocks but should not detach from it.