Tbh I don't think fighting open source is Google's best play. I think it is in their own best interest to keep it fully open. It is free labor by those who are most passionate. It gives strong signals at what people want, this direction you develop. It strengthens security as more people try to test it. It means people work on forks rather than alternatives. All this is true even with a monopolistic market share.
So yes, I do think they are being naïve. The stance is myopic. It is only a good move in the short term, and barely even that. It is under the false belief that we operate in a zero sum game.
Google learned that it's exactly not in in their best interest when they lost their court case against Epic a few years ago which is why they are shifting focus away from open source and moving towards Apple's walled garden approach. If they had locked down their platform similarly as Apple did, Epic would probably have lost it's case for similar reasons.
Granted, we know Android would not be where it is today without open source contributions.
Most successful open source projects have devs being paid by big corporations, including Linux itself, which only really took off in the 2000's when companies like IBM started caring.
Also in the last century most software was commercial, and thanks to business friendly licenses we are back to demos, PD, Shareware and co, only with new names for a younger generation.
Google will do just fine.