Key Bank bought the naming rights and named it "Key Arena." Amazon bought the naming rights and called it "Climate Pledge Arena." The only sense in which one of those arbitrary names is "virtue signaling" and the other isn't it that some people just don't like it when anyone mentions climate change in public.
Amazon doing it doesn't make it any less virtue signalling. I'd be much more impressed if Amazon had used the money instead to buy some forest land and turned it into a nature conservancy. I wouldn't be critical of calling that "Climate Pledge Park".
And also, the whole reason Amazon named it that is because they are pledging to make the arena powered by renewable energy. You can certainly argue how significant that is, but it certainly doesn’t seem all that different from buying a park and naming it after climate change.
