It seems to me that Musk's eco-credentials have been long largely abandoned, assuming he every really had them to begin with. I get the sense that they were only ever useful to help sell cars and support his ego-trip (make him seem a "visionary"). None of his other projects are particularly eco-friendly (a tunnel, but just for cars, big rockets, autonomous cars rather than larger scale transit, etc.)

I think the more likely reason Musk and Trump will fall-out of... whatever it is they have... is they both have huge egos and don't like sharing the spotlight.