I imagine avoiding IP legal issues with things like icons could be less about signing agreements with all involved companies and more about having a team that can respond professionally to an inquiry.

Businesses may often not really understand what’s going on and default to being worried about third-party use of their trademarks that they normally must defend. Perhaps they don’t need to worry in this case, where it may actually provide a bit of free advertisement, but if there’s no one on the other side then it wouldn’t help the case.

IANAL