IIRC, his "LibAV" fork was malicious and his people lied a lot to the community ("ffmpeg is now deprecated!"). Ultimately, they failed, but I see a lot of their rhetoric and resentment in Kostya's post today.
And if you browse through the ffmpeg mailing list of that historic month https://ffmpeg.org/pipermail/ffmpeg-devel/2011-January/ you'll find his name mostly attached to esoteric video game format patches and not in the big flamewar threads.
Actually - it looks like you can also see in that same month, his post of the first SMUSH codec implementation, that we're discussing in this thread. That's probably a bigger emotional factor than LibAV.
That's my point and also why I won't dig more. The author hasn't come to terms with his bad experience with ffmpeg, in LibAV or otherwise. Whatever the baggage is, it feels quite messy and heavy. It weighs down the article, with too much bitterness and resentment. That could work for self-therapy, less so for a credible account. As he confesses at the end:
> I wrote this post with an ulterior motive—I don’t want to feel shame when remembering that I took part in that project. So far though the more I hear about it the more disgusted I become.