If you can find the arm, yes, remove it but don't tear up the tank looking. However, I don't recall anyone ever finding a truncated arm in the tank. Do you have ANY impellers (in-takes for a power head for example) that Beans might have investigated and then detached the arm because it got caught? The only spinning things I keep in the tanks any more are the Koralias, which were successfully designed to avoid sucking in most live things. They made me nerveous around OhToo for months but, inspite of his poking, he never damaged himself and this had held true through several others of mine and everyone else who has reported using them.
If your zoos keep getting moved, I would suggest relocating them. It takes quite awhile for them to attach (some people glue them or put a netting over them for three or four weeks) so if they are being blown around, they never will.
I have not kept an abdopus for more than a couple of weeks (he was known to be senescent when he arrived) so I can't give you direct observation on this species. In the spirit of trying to help you not get frustrated, I will tell you that we tried to watch the regrowth rate with SueNami and have guestimated it at about an inch a month. I am sure, however, that the hummelincki regrowth rate was slower but we did not make an attempt to record any observations.