If we read the rest of that thread they are but not changing the name. They are adding a tag stating it has an alternate name.
Adding an alternate name in an obscure tag that is not surfaced on most renderers is not the same as changing the name. Nobody is changing the name. You will still see Lake Ontario on OSM for the foreseeable future. It’s okay, you can put your pitchfork down.
If we read the rest of that thread they are but not changing the name. They are adding a tag stating it has an alternate name.
Edit: fixed typos.