a bunch of lower leveled vampires, none of which are under protection but 1
They are
all Clerics of Hel(they're wearing Unholy Symbols), so they're all under protection from The Rules. If a Cleric from one religion attacked another, it'd start a holy war, something the Godsmoot is supposed to avoid. Roy attacking Durkulon doesn't count since he's not a Cleric, and was in service(though he didn't know it) of the High Priest of Hel.
I did notice that the two female vampires whose Unholy Symbols are visible are also reversed from the men's.
Those new vamp spawn are looking pretty hostile.
Not the one standing by the arch. She looks mildly interested in what's going on at best.
But seriously, how many charges did that staff even
have? And it was already heavily used to begin with,
given Malack and Tarquin's discussion here about the mummies taking a few charges each. So far as I can tell, a single charge is good for 3 spell levels.
By that logic, Create Undead(the mummies) is 2 charges - I saw seven mummies in that strip, so 14 charges. No idea on what spell would create full Vampires, probably Create Greater Undead(3 charges) or similar effect. I'm seeing ten in this strip, plus the use for Durkon and that Goliath that Belkar ran into. 36 + 14 means that the staff would have been completely charged the moment Malack started making mummies in order for to have managed it completely.