Graham told me in a followup email that he was indeed serious and had just given the list of SOPA supporters to the people in charge of the Demo Day invites
It's not PG who needs to know, it's the people he's put in charge of Demo Day.
Yes, I read that too, and that's my point: he doesn't make the invitations himself; just because you trust an organisation to do something doesn't mean you can dispense yourself from verifying they did what they were asked to do.
The "people in charge of the Demo Day invites" probably have enormous incentives to invite influential and powerful employees from SOPA-supporting companies, and would certainly face backslash they'd rather do without.
So what I think is happening is that PG just added "manage invitations to Demo Day" to his todo list... (all the most admirable BTW)
The people in charge of the Demo Day invites work for PG. They're just running an event, they don't care if any specific organisations attend it apart from the criteria given to them by PG.
Oh well, if they're simply Y Combinator employees it's as you say; I read that as if it meant they were a contractor ("the people in charge" vs. "us/we").
Graham told me in a followup email that he was indeed serious and had just given the list of SOPA supporters to the people in charge of the Demo Day invites
It's not PG who needs to know, it's the people he's put in charge of Demo Day.