Just watched it twice, and here's what I think:

Cook was really messed up and you can see he sort of stumbled a bit trying to get up after the 2nd knockdown. I think the ref saw that. When a fighter tries to get up and stumbles, it usually is a sign of significant disorientation, such that 10 seconds will not be sufficient for his recovery. One more blow and serious damage could occur.

I do think, however, that the ref should have asked Cook how he was, and should also have had Cook take a few steps forward towards him, before just waving his arms the micro-second after Cook got up, and to his credit he did beat the count.

The ref should have observed Cook for another 1-2 seconds AFTER he was up before calling it off.

If I were the ref I would have let it go more. But the ref was within his jurisdiction to rule as he did, due to the "knee-stumble" of Cook.