It's more like some other people got sick of that guy coming up with baseless assumptions, and (more importantly) baseless assertions, in order to support his goals; and a few of them don't let that go any more.
Because that's a constant pattern for him (he's been Perl's pumpking for several years, and then part of the ruling trio since the change in the governance system caused by the aftermaths of the announcement of his Perl 7 "plan"): he comes up with a change, or a plan like the Perl 7 plan, something that on the surface seems researched and based, and then... he backpedals because he is unable to sustain his claims, or he is proven wrong by people who actually know what they are talking about (with testimonies of recognised people, data, facts forming a consensus), or it becomes clear he didn't study the consequences of his planned changes (again, other people have to put up with the work needed to study that).
And sometimes, after a consensus has emerged and he either (seemingly) caved in or played possum (after all, both are more or less fine in a real human interaction, no need to publicly acknowledge every "defeat"), he comes back with the same points which have already been disproven. For example, this time he was arguing with some invisible authority arguments. While real data, real testimony of trustable people is sitting there and say the opposite.
Since I follow Perl 5 mailing lists in the recent years, he exhibits that same behavioural pattern. He probably doesn't even do it on purpose, he probably means well, he probably thinks his propositions are well researched and all. But he doesn't learn to do better for the next time.
Also, yesterday or 2 days ago, the Steering Committee trio of which he is part decided that for Perl 7, the decision would be to side more with the majority of Perl 5 core developers (that's a manner of saying it which is very abridged, but well...), than with his original plan. So you've got to keep in mind that his burst comes after what he probably felt like a disavowal, and this might be either the real reason, or a fair part of the reasons, rather than this alleged sea-lioning.