The Heisenberg is an especially powerful card because it is always what you expect it to be - ALIVE, DEAD, or EMPTY. So, if the Hypothesis is about Alive cats, the Heisenberg counts as an Alive Cat. If your Hypothesis is that the cats are dead, then it counts as a Dead Cat.
IMPORTANT NOTE: A hypothesis of Heisenbergs (the quantum wildcards) is never allowed, because you can’t see the inner workings of the cosmos!