I blew up Vault 19 -- so why does the ending act like I didn't?

I just finished New Vegas, siding with the NCR. This was my fourth run-through. This time around, I blew up Vault 19. (It seems that being "Very Good" karmically involved a lot of blowing up established environments -- Vault 19, the Brotherhood, I could go on ... )

So I get to the end-game, and I'm told that the Vault 19 Powder Gangers continued to torment the wasteland for years, preying on citizens of the NCR.

What? I blew them up. Like, exploded the Vault. Kablooey! Is this a glitch, or does the game just not have a separate ending slide for, "the Courier destroyed all the evil ex-cons and the NCR lived happily ever after?"

According to the Fallout New Vegas Wiki you have to talk to Philip Lem about the future of the Powder gangers, otherwise you get the incorrect ending. There are four different endings for the Vault 19 Powder gangers.