Marlow is _full-time_ at Facebook, bye bye. There's a difference between being a ghc developer and THE ghc developer. He's more of an advisor now than a committer, look at his ghc commit history, lots of comments, few commits.

Not saying he's joined the dark side like Erik Meijer, but he's also not actively _working_ on the compiler as he did before; that's for the new guy(s).