Party-pooper time:
... would this have been greeted with the same hilarity if it had been Osama bin Laden? ... or Howard Shipman (look it up...)?
Scrooge
Mocking the mental anguish of criminals against humanity is just fine by my book. As opposed to say lauding them or showing them any sort of respect of any kind.
It's an internet meme. No different than all the different rants that have been attached to Christian Bale's meltdown on the Terminator:Salvation set. (In that case, its just funny to mock the incredibly self-indulgent outrage of someone way too full of himself for his own good).
Is either one in "good taste"? Probably not - the 'warhammer' reference alone guarantees that. But yes, if Osama were similarly spoofed and made to look like an imbecile, I'd find it very funny. Preferably if same was done after he'd been caught and appropriately sentenced for his crimes by a suitably reserved court of law (vs. the unfortunate spectacle that Saddam's trial became). Mocking the memory of monsters is (one hopes!!) one way of remembering them and hopefully innoculating society against future equivalents. I know, I'm dreaming there. Humanity will just introduce new and totally different monsters. Merry Xmas-Eve thoughts... 
As for Shipman, did you mean Harold perhaps, serial killer British Dr.? Might not be well known enough to be globally funny if so mocked. Don't really recall much about that story myself....
