Much of the controversy around this stems from the fact that he said the "app" is doing RPCs instead of the endpoints which it calls, that in turn assemble the instructions to render the timeline?
Seems like many are going out of the way to frame it as nonsense.
It's dubious that this only affects some countries. Is it likely that there are some extra pieces of logic for some parts of the world and not others? My guess is yes, although it seems unlikely that the impact would be so high.
As for this specific issue only affecting Android - that was never the claim. Instead he asked an entirely separate question about Android performance to this developer who replied to the tweet with the original claim.
Overall, aside from this specific incident - his attitude towards the way the company way being run is extremely hostile, and has naturally upset a lot of folks at the company who were happy with what they were doing.
Personally, my view would be that if this happens and it bothers someone a lot, the honorable thing to do is to quit or sit back and watch the company fall apart and own their bet that the new direction will be a disaster.
If one is not on board with the vision and direction of the company from new leadership, quit instead of getting in the way.
Actively sabotaging the company's new direction is not only immoral but also reflects a mean-spirited attitude towards one's fellow co-workers who don't share that view. I have seen tweets from current employees calling their fellow team members bootlickers, etc. which I find to be quite vile.
Seems like some folks are likening the whole thing to a Cardassian occupation.