Don't misrepresent where you went to school.

[alexf.1990]

Are HES allowed to join the Harvard Alumni Association upon the conferral of their degree?

They are. They're also allowed to join the Harvard Club. From what I understand, the HAA isn't as valuable for networking as the alumni associations of the individual schools. The Harvard Club appears to be just a social club for people who graduated from Harvard College to talk about the good old days, so membership isn't worth much for someone who can't bond over experiences on Harvard's campus.

That is 100% opposite of the Harvard Executive Education alumni.  These alumni (HKS can be as short as 6-days) can only join the individual school alumni, not the Univerity one.  They join the Harvard Kennedy School, Harvard Business School (HBS), etc.   These types only care about their own area.

I suppose their rationale is that anyone well off enough to pay 30-50k for a week long course belongs in their inner circle.