If the pvp players didn't want to face BGS pvp they shouldn't have a BGS element.
That's the funny part. Attacking them where they're weak is smart. It's sound tactics. That's not the issue at hand.
Being angry enough to drop what you're doing and waste your time attack them
at all is the real goal. It's the internet troll's classic "you care about this whole thing more than I do, ha ha ha". It's
funny if someone gets mad enough to trash your sandcastle which you can trivially rebuild when they move on, if you can even be bothered.
It's a big target they can put up there and laugh as people dash themselves against it in a fit of rage, because watching their influence plummet after a gank is like a juicy angry reddit post to them. Hell, the biggest tactical mistake they made IMO was that most of them made their factions anarchies - not because of the usual stuff about anarchies being BGS underdogs or anything, but because being an anarchy means they can't point and laugh at the bounty board.