McCain made a direct accusation against ACORN on TV, accusing them of trying to undermine democracy in the way they were registering voters, virtually accusing them of treason. The accusation, presented as if it were a proven fact, has been been repeated many times. It's not unreasonable that ACORN should seek to rebut those charges.

The voters registered by ACORN will be free to vote for whomever they choose to vote for. Presumably a good number will in fact be voting for McCain, assuming they don't get disenfranchised as a result of the tactics adopted by people in his campaign.