Didn't he also refer the bell curve studies that claim that despite the same average intelligence, there are less 80 IQ women than men and there less 120 IQ women than men? So why wouldn't it be reasonable to assume when he was talking about IQ differences, he was talking about that?

Why do you jump to the conclusion he must be talking about ethnicity? Afaik ethnicity wasn't referred to at all in his memo.

He repeatedly refers to race in the context of diversity in his memo, at least 9 times the word "race" is used for example. Notably, he doesn't seem to feel the need to back any of that up with science, apart from (maybe!) the casual reference to IQ.

Sometimes you'd think there were two completely different memos under discussion given the lack of basic agreement on facts as relate to the memo itself, never mind it's arguments and sources.

Though, I guess you're right, he may have left it ambigous about exactly which IQ differences he believes in that "the left" don't. People seem to think it's wrong to complain about his communication style, but as this example illustrates, peppering a memo with alt-right buzzwords and then being ambiguous about which particular controversial IQ studies you support can just as honestly be interpreted as dog-whistling rather than incredibly high levels of naivety. I think most people suggesting his communication skills are lacking are actually just giving him the benefit of the doubt.