This is because autoconfig itself is not controlled by the vampire, but by the buster chip on the mainboard.
A500, so there is no buster. CFGIN/CFGOUT don't seem to be handled by buster on the A2000 either, the slots are looped with an 74LS chip to allow empty slots to be skipped. If the vampire prevented access to 0xE80000 then you wouldn't be able to configure the card, it could also prevent access to zorro 2 ram or io space which would allow the card to be detected but not used.