To base the decision on what companies to invite to an EV summit on whether they support the Democrats' favorite constituents is pure politics. The only policy difference here is one which helps the Democrats win elections.
Democrats believe that unions help keep wages high and are good for the economy.
If Musk wasn't anti union he probably would have been invited. I say probably because of Teslas issues with racial discrimination
As for the claim that Tesla has racial discrimination issues—that’s a distortion. Nearly every major company gets hit with discrimination lawsuits because civil rights law has been weaponized to make that outcome nearly inevitable:
https://www.richardhanania.com/p/wokeness-as-saddam-statues-...