Apparently, not only is he now locked out (so I've heard, not had the chance to try), but the seraph crystals obtained from him don't contribute to 'In the Pink'.
That really sucks. I know it's optional, but it would be nice knowing that I wouldn't have to suffer through Gee or Hyperius again to complete some challenges. Pete has been the first raid boss that I actually had fun fighting. That was a good fight.
Does the same apply to buying seraph items? Does it not count towards that challenge if purchased in the Badass crater? That would suck even more; the items in this vendor look pretty decent. The ones in Oasis just suck (bar the relic, and possibly the Evo shield).
Either I give up on those challenges, or I try to put up with the tediusness and bad drop rates of Gee and Hyperius.