Bob Bauer responds here. I am not convinced by Bob’s distinctions. Why is it corporate speech when the NRA (a grassroots organization) speaks but it is individual speech when Michael Moore speaks? Moore, of course, is not funding ads for his movie himself. They are paid for by a foreign corporation.
There may be good reasons to exempt both (or neither) from the electioneering communications provisions. But I don’t think the distinction Bob draws is persuasive.
UPDATE: A reader writes:

It’s actually anti-persuasive; Violate Moore’s rights, and you violate the
rights of one man. Violate the NRA’s rights, and you’re violating the rights
of four million men and women.
After all, it’s not like the NRA exists for some completely different
purpose, and it’s resources have been hijacked to advance an agenda the
corporation’s members wouldn’t agree to. That’s a fair description of
Moore’s case! The NRA exists specifically to give it’s members a voice in
instances like this.It’s not a hijacking, it’s more of a charter flight…

Thanks for writing.
UPDATE 2: Bob posts here what he characterizes as his “last word.” He still does not grapple with the fact that Moore’s spending is being done by a corporation, and a Canadian one at that.