I don't think he was talking about the "Progressive Conservative" party. Just "progressive" Liberals using this tactic, when the chips are down. It totally wouldn't shock me if this was dug up by the Liberals, considering how they're polling. The timing is a bit suspect.
That said, he didn't have to step down, so it's equally the Conservative's responsibility in setting this precedent, and it's fucking pathetic. Want to beat your opponent? Just drag some chicks out of the woodwork from their past, and have them accuse him of "sexual misconduct", over some flirting and having advances turned down. Extra sympathy, if you were a poor silly little girl who had drinks literally forced down your throat at the bar, by that evil piece of shit male. Now step down, you fucking monster.
If this is all there is to the story, it's fucking sad. Especially on the Conservative's part for caving so easily.