Fourthly, the Nords are not the most racist. That honor easily belongs to the High Elves/Altmer. Try being a Nord living in the Summerset Isles. Oh, what's that? Oh yeah. You can't. They won't let you.
Thalmor =/= Altmer. Thalmor slaughter as much of their own Altmer kin as they do Nords. Many Altmer fled the Thalmor to hide inside the provinces of man and warn them of the Thalmor, only to be hunted down and killed like dogs. The Night of Green Fire for example.
Try being a Bosmer under Thalmor rule, wondering if you're next for the purges no one ever hears about.
Yes, all Altmer are indeed not Thalmor. However, as they were judging Nords based on the worst among them, it seems entirely fair that the Altmer would be looked at under the same light. I did not mean to call all Altmer racist, even though that is indeed exactly what I put. What I should have said, more correctly, is that the most racist organization in all of Tamriel is composed entirely of Altmer; the Thalmor
Let us compare Thalmor and Stormcloaks.
The Thalmor actively hunt down and kill dissidents even in provinces that are not in their possession. As you posted, Hammerfell. Also in Skyrim. Meanwhile, the Stormcloaks have Dunmer living in their capital city who absolutely loathe them, and Nordic dissidents as well. While they're not treated greatly, they certainly aren't slaughtered.
I'm not entirely sure what your last point was? I certainly did not intend to imply that the Thalmor only hate Nords. No, I think it's entirely fair to say they hate all non-Altmer races but are willing to tolerate mer over man. And even then they're extremely watchful over Altmer.
I think it is fair to say that the Thalmor are the most racist organization in all of Skyrim because not only do they actively hate every other race, but they also want to conquer them, oppress them, and/or kill them. The Stormcloaks haven't even kicked the Dunmer out of Windhelm.