Don't cut yourself.
Occam refers to two competitive scientific theories. I can't see another one. If you got ID in mind. Please keep it there. ID has no explanatory power.
Even the researchers said that they found a mere 8000 years to be remarkable fast for the development of a new species.
Might the incompatibility be due to another organism, parasitic or otherwise, that the other frog population had not been exposed to affecting interpopulational fertility?
Moving them to a lab would not necessarily get rid of the parasites, virii, etc..
Did anyone check for that or were they in such a rush to have their ego step on someone's ID?
There is your other theory.
I asked, you flamed. Lovely science.