That would require houseruling in extra subtypes, though. Humanoid is a specific unusual case because every humanoid also has a subtype of elf/orc/dwarf/human/whatever. Something like Undead, on the other hand, only has one common subtype - Incorporeal. So you'd have to add the [zombie] and [skeleton] and [vampire] and [whatever] subtypes to make it work for undead, and appropriate equivalencies for others. Assuming you do so, I can see that sort of houserule working out, but it isn't plug and play by any means.