Lots of people keep apolemichthys in a reef. bandits are commonly seen in reefs, as are the flagfin's close cousins the goldflake angel. All angels are a risk but I would not go so far as to say are not reef compatible, they would be solidly in the with caution category. If you have a large acan/scholy/trachy/favia collection then I would not risk it but if you have mostly sps then it can be a fine fit.
Great video that talks in depth on the topic at general and specifically on keeping the somewhat closely related bandit angels in a reef tank.