I've got no problem with the writers and performers of Mystery Science Theater 3000 who are now associated with RiffTrax and Cinematic Titanic. Their previous work in the field earned them movie riffing chops, and now they're running with it. BUT I think it would be a bad thing if only people who happened to work on that show in the 1989-1999 period are now eligible to be legitimate movie riffers. Most of the RT/CT sure weren't there from day one; it's nice to have some fresh faces for the future. So this is why I like to give a little highlight to the few new folks for whom it's their primary job, as opposed to the RiffTrax Presents and iRiff people who are more dabblers into it.
Cinematic Titanic having five former MST3K people, they seem pretty solid with their current lineup for now. RiffTrax having fewer ex-MST3K people and a larger output is where the action comes in.
Conor Lastowka seems to have been with RiffTrax/Legend Films at least as long as Mike; he's present in the short "Mike Nelson Goes to Work at Legend Films" YouTube videos from mid-2006, though based on Bill's wording in this post I'm not sure he was working as a riff writer from the beginning.
Sean Thomason is the second addition to the RiffTrax writing crew. Same Bill Corbett post as from above mentions him as being one of a few writers put to work on the first draft of one riff in mid-2008, and he seems to be the one that ended up a full-time presence as of late 2009.