[tnmrnis]

He was suggesting that Megyn Kelly was asking him though questions and that the reason for this was that she is on her period. There is a very subtle but important difference.

He attacked her for asking supposedly though questions, not for being on her period. First was the reason of his attack. Latter was the means of his attack.

[foldr]

As with the other reply, I don't see how this is any better. It's still openly sexist. (Megan Kelley isn't able to do her job properly because she has a uterus.)

[sjwright]

Let's assume you're right. How is that any better?

[tnmrnis]

Her sex wasn't the reason he attacked her, therefor it wasn't sexist.

[PavleMiha]

He's implying that women on their periods have their judgement impaired, which, considering that only women have periods, is sexist and false.