It's...it's...possibly one of the clan members of the Elite Dangerous 'Oldtimers Rotary Club' !....they do this to signal to others in the area that they've found a honey mine....you can see quite clearly the mine entrance on the asteroid surface.
Sheesh!....don't you beta players know ANYTHING?!...
The behaviour I think is caused by whoever was hosting the AI for that NPC disconnecting. They usually go in to a spin and Bryant there seems to have got stuck on the asteroid.
Bryant has killed me more than any other NPC too. He has an annoying habit of interdicting me then following me in to other instances.