Show me the intelligence ...

By that reasoning it's not possible for anything, natural or otherwise, to not be designed. Ergo you've proposed an unfalsifiable model.

Impossible to say. It's unfalsifiable. Yes. And unfalsifiable theory explains nothing and is of no use, regardless of whether or not it's "right". Because there's no potential situation where it could be definitively refuted, there's no way to know if it's right or not. If every single thing that could exist is the product of design, how would you know if anything is?

I think his point is that it's poor design to require sperm production to have to occur at a lower body temperature, necessitating the external testicles.If I were God, and the guy I had design Woman showed up and was like "well, they're going to have to do this 'mensturation' thing," I'd send him back to the drawing board. But that's just me.