Without actually checking I can only presume the "universal quitkey" (independent of the slave) works by using the vector base register (VBR) and mapping the interrupt vectors outside of the zero page. Then the new interrupt vectors check for the key before continuing to the real interrupt vector pointed by the zero page.
VBR was introduced by the 68010.
@ dougal
And I believe that's the same reason the Quit key doesn't work if you use the NOVBRMOVE tooltype.
There are a few games that use a different method for the quit key, so you might find those working, even on a plain 000.
As others said, you can get an 010 pretty easily, and it's a simple drop-in replacement on the A2000
