I find it difficult to believe that pvp costs more money. They have a pvp system already. It is just a question of designing a bg environment, and that can be just cut-and-paste off the world. Mess around with something like "Second Life" where you can terraform stuff and it isn't particulary hard. A bg should be less work than a selfie camera.
I agree with you Kotick is an unusually revolting asshole who has played a big part in wow's decline, but I can't find any direct quotes about pvp.
He probably means it costs more money per player. Fewer players play pvp so..