like MapQuest did.

MapQuest didn't really do anything, it uses OpenStreetMaps which is a community effort and doesn't have localized place names the way Google and Apple maps do. E.g country names for me in google maps aren't their local names, nor the GNIS names you'd see in the US, they're names in my own language. In Google on particular, there's literally no "United States" on the map, only "Ameerika Ühendriigid" for me, Apple has fewer localizations but still shows many things in Estonian to me. There's a large degree of automation there for them to do this in I'm assuming 100+ languages for anything they can (i.e country names and large bodies of water as well as many cities are in Estonian for me, but most other places are just global defaults). Once you start adding manual overrides, shit like this gets way too difficult to manage for little reason.

When he was changing name of Gulf of Mexico they didn’t have problem to make it show only four US audience.

So same as Lake Ontario. Because when you're in the US, it pulls names from GNIS as far as I know, and in other places it has other sources or just static datasets of their own. I still see Ontario, the global default, in both Google and Apple maps.