Google has used its weight to build a technically better product, won the market, and are now driving the whole web platform forward the way they like it.
This has nothing to do with the cost of maintaining the browser for them.
I'm not sure what else it would be about - I don't see why they would especially care about removing XSLT support if cost isn't a factor.
There is this weird idea that wealthy people & corporations arent like the rest of us, and no rules apply to them. And to a certain extent its true that things are different if you have that type of wealth. But at the end of the day, everyone is still human, and the same restrictions still generally apply. At most they are just pushed a little further out.
I am sure they've got good reasons they want to do this: them having the same problems as an unstaffed open source project getting vocal user requests is not one of them.