Linus should have stepped in earlier. The R4L guys have been running against walls over and over (just look at how T'so, the "thin blue line" guy, spewed hate at that one conference), because individual developers think they can use their power to slow down the R4L project. They don't argue on a technical level. Linus, as the project lead, has to step in when this happens, otherwise the experiment can't work.

To add nuance to my comment: I think that Linus mismanaged the conflict, and that this was a significant and avoidable factor in Marcan getting burned out. For an example of how Linus could have approached this instead: he could have publicly criticized both Marcan and Hellwig at the same time, rather than first publicly criticizing Marcan and then only after Marcan left publicly criticizing Hellwig for his own behavior. This probably would have made Marcan feel less picked on and less likely to have been burnt out. (Or maybe not; I do not claim to deal in certainties.)

The contributor's frustration with Linus started with Linus ignoring multiple explicit requests for his intervention. When the contributor was so frustrated at the lack of response from Linus that he had the audacity to talk about it off list (linking here because the original toot has been deleted), it was at that point that Linus finally chimed in to tell the contributor "Maybe the problem is you," implying that Hellwig's obstructionism was not a problem in his eyes and that the only issue was the contributor drawing public attention to it.