I suspect that Greg has started to feel the "cognitive dissonance pain" that seems to be in an advanced stage with Luke.  Subject has believed in X for some years, but when he brings X to a wider audience,  some strong arguments against it come up. Or most people intensely dislike some consequences of X that the subject thought were good or insignificant.  Not prepared to change his mind, subject instead adopts some belief Y that supports X, which turns out to be even less valid than X.  And so on, the subject keeps building an ever larger edifice of ever more unsustainable beliefs, all in an attempt to save X.  When that becomes impossible, the subject just refuses to think about the counter-argumens, and runs away from public discussions.

Some convicted small-blockians, like Greg and Peter Todd, have held for years belief that the fee market and off-chain systems would be the solution for bitcoin scaling.  That belief was set in concrete when Blockstream was formed and incorporated it in their business plan (and ditto for Viacoin).  But once they presented the "fee market" to the world as an imminent imposed change, rather than an idle speculation, Mike, Gavin, and many others have pointed out that it would be a disaster for bitcoin.  But they cannot back out of it now...

Some of the "Y" beliefs that they had to accumulate are "wallets can be programmed to compute the right fee for a given delay"  "larger block size limit means miners can post large block sto gain unfair advantage" "miners and businesses do not control the protocol, it is the realy nodes and the developers who matter" "there must be only one implementation of the protocol" "a consensus means two developers agree on a change" "larger block size limits will increase the load on relay nodes"