It is OK to ask questions about games under playtest; we facilitated tons for the D&D Next Playtest as you remember. Answers will be a bit volatile, so sometimes answers will go outdated and new ones will arrive — that's to be accepted with the territory.
(Just don't break your NDAs if you're under oneany. Some playtests take place under NDA which probably means nobody can meaningfully ask or answer anything about that playtest. We don't have any questions about the Fate Core playtest for this reason.)
That particular question wanted a comprehensive edition comparison, which seems like too much to ask during an unsettled playtest. I'd say we should hold off on edition comparison questions for games under playtest, but that's only my subjective judgement at the moment: the community may disagree and so might my fellow diamond moderators.
I think we should be using a pathfinder-2e-playtest tag for playtest materials. Once the full game is out we can use a pathfinder-2e tag instead, and people can ask about the finalised version there without potentially getting cruft from the playtest filling the tag. We discussed the idea of doing something like that for the D&D Next playtest (Revisiting whether D&D Next needs its own separate tag, Can we rename [dnd-next] to [dnd-next-playtest] before it's released?) and only afterwards realised the utility of having a dnd-next-playtest tag, and I think we should be doing that in advancefrom the start this time.