So win-win really. Either vampires would be dusted, or they'd be souled humans. I guess it goes back to @thrasherpix's original question. Angel probably should have told someone responsible (Watchers' Council?) about the effect, so they could investigate the effect.But seriously,I think this is quirk caused by Angel having a soul, any other undead would probably just purify and cease to be undead, as opposed to live again.