They were put in an untenable situation, IMO. If they said no, there would be howls of protest, and a possible schism in the community, and the next SC elections could be an ugly competition between pro- and anti-GIL advocates. A "yes, but..." approach was about the only option.
They do recognize the impact on the ecosystem will be huge, they recognize there will be at least 5 years of parallel gil/nogil versions(*), and they say they don't want a 2-3 story all over again.
Yet they have decided against their own best advise (to avoid such a situation).
It utterly confuses me.
(*) not just one parallel version, there will be 2 for every release following the introduction. In reality organisations will have to maintain 4-6 different baselines of Python releases along with a matching (and likely differing) set of libraries. I don't mean to fearmonger, I just happen to maintain such environements and I know the effort that goes into this first hand.