I don't think that licensing terms is the right term here. But IANAL. I'd call it licensing terms if you are using the license of the trademark holder to do something with the icon, like marking a product of your own. That's not happening here. Feather is distributing icons of brands (which is legal) or icons that resemble those icons of brands (still legal) to people that may use them to depict those brands (for which one does not require a license).
Oh, seems like I'm out of my depth there :/ I do understand that copyright might apply, but not how it could make such logos problematic (in US-law, right?). In which way can such a logo be infringing derivative work?
