Kind of a shit move to suddenly pull the rug once they've finally gotten it working. Should have been kept out of main from the start.
I suspect the recent "we updated the GC without a PEP and it went live and caused massive issues and we need an emergency point release revert" pushed for a greater degree of process overall.
The post clearly says the intention is to get a formal spec for formal integration.
To leave their experimental phase they have to define some goals to meet and that requires making some architectural choices that still aren't decided.