I saw an interesting program on Discovery channel about reefs and they mentioned divers have just discovered the clown fish/anemone symbiotic behavior spreading among other fish in the reef. Your case, we're not dealing with either a clown nor an anemone, but I would imagine this angel realizes the benefits of hanging around the torch coral. Perhaps even learned in the reef before capture. There is always dangers due to the coral's toxic stings just as there is always a danger for clowns within their anemones, but I'd take this as a good opportunity to observe a very recent discovery. Quite interesting
Even clown fish need to 'prepare' themselves to be able to co exist with the anemone without being detected as a fish. I've read that clowns are not immune to the stings of anemones and the wiggling behavior provides two main assets to the clowns. It masks their fishy scent to that of the anemone, so the clown isn't recognized as a fish, but part of the anemone and helps excrete an extra layer of protective slime to help provent the anemone's tentacles from penetrating the clown if they do go to sting.
This behavior was witnessed mostly with hawk fish taking residence in anemones as well as gobies. The study is looking into the possibility of learning capacity of these fish from this newly observed behavior. They believe the other fish that they've seen use anemones have learned this behavior by watching and mimicing the clowns.
On ocassion I have seen clowns and damsels take to types of coral such as bubbles, torches, hammers, frogspawn...just about anything with long flowy tentacles in aquariums. I even witnessed a tomatoe clown treating a fake plant like it was an anemone. It was entertaining to watch her attempt to feed it...LOL.
If you feel that uncomfortable about it, you can always try moving the torch. The angel may or may not follow. That would be interesting.
Well, those are my thoughts
We, as a people, know so much more about outer space than we do about our own oceans. This lack of knowledge can very well spell the dangers that lay in wait for us.
The oceans surely would swallow us before a rock comes down to smite the planet of it's life.