Hi hello.
I have a magnificent and its very skittish. However, mines an open swimmer and LOVES nori - itll tear up a whole sheet easy. I've had two one spotted in the past and nvr had any problem them stabbing me. I am more afraid of clowns more than anything lol.
Get one spot ff , the magnificent ara a tad bigger in general. Also, they are hard to net bc of their spine - itll get caught up in the net.
But yea, absolutely zero concern about the spine. Like other have mentioned, there are other things in a saltwater aquarium that is way more dangerous. I've picked up a rock and got stabbed by vermetid snail and got bit by bristle worm, and let me tell you.. hurt for days !
Cheers from Texas