It's a matter of perspective. Oyvind doesn't see himself as GIMP hacker. That's what I heard him articulating multiple times. Good luck persuading him that it's otherwise :)
I'm afraid that you are doing rather quantitative analysis without referring to timeline. Martin hasn't been doing much in Git since last spring. I've been doing weekly digests of changes in Git for about a year, so I kind of watch that. If you are keen referring to Ohloh, look at the timeline and do comparative research re amount of commits for e.g. Martin and Mitch. You'll see what I mean ;)