The claim that someone in a clear position to create problems is simply musing abstractly (“Nice factory ya got here…”) is disingenuous even by your standards.
Yes?
That’s absolutely his opinion. He’s offering his prediction, based on his claimed conversations with a specific source he does not name, that if the UAW is rejected, VW will bring their new SUV to Chattanooga. He certainly has no authority as a senator to force them to uphold that bargain, if even they made it.
Undoubtedly he has more opportunity to be heard than Joe Schmoe on the street, but it’s equally obvious there is no senatorial authority behind what he’s saying – how could there be?
‘If I wanted your opinion, I’d give it to you!’ 
What kinds of problems are you picturing?
I mean, I guess it’s possible that Senator Corker would make up some dire scenario that had absolutely no chance of actually happening. Maybe he could say something like, “I consider it a matter of established fact that VW will close its plant here if the UAW gets voted in.”
But that would be really irresponsible. I can’t imagine anyone arguing in good faith doing that. Can you?
Rather than the company that’s actually making the decision not to expand? I thought from the other thread that conditioning negative consequences on the outcome of the vote was essentially blackmail.