ask yourself: what test can we make that would disprove the theory?
maybe i'm just not smart enough to come up with one, but i can't conceive of one. an untestable, that is, an undisprovable hypothesis, is an empty tautology. or, at least modern epistemologists and critical rationalists have treated them this way.
maybe disprovability isn't a necessary facet of sound scientific theories. i tend to agree with popper, though.