"everyone" was a poor choice of words but he does mention the note ordering an attack on him in the OP and says they attacked him directly so that rules out the traveling justiciars or prisoner escorts.

What you've quoted is what I was asking him about as those are the conditions for his attack but it's no surprise that many like you or Aurora have experienced a bug where they attack without those conditions. Personally I've never been attacked without completing Diplomatic Immunity or rescuing Thorald but this is Skyrim we're talking about where it's been known to rain mammoths at times

Perhaps she doesn't like another powerful elf woman running around in Skyrim

The same thing happens without ever doing anything to provoke them. I have seen the note ordering my execution for disrupting ther activities on numerous occasions.

It's not a bug. As stated previously, the only requirement for this encounter, according to UESP, is to reach level 8.

I've had this encounter in pretty well every run-through I've played. My current character 'bumped into' the assassin squad near Gjukar's Monument at level 12. Hadn't attacked any Thalmor, hadn't spoken to Fralia, hadn't been to High Hrothgar.

I got some attacking me straight out of Riverwood, when I was heading to Whiterun for the carriage. >:

Though funny thing, Gilliam was suppose to actually try and sabotage any Thalmor in Skyrim, so it fit well.

Probably a glitch, Gilliam was level 4 at the time.

You say it as if it were a bad thing. Any Thalmor foolish enough to kill your character deserves the fate your character dishes out on them.

Drown them with bunnies!

They are actually not that hard, and you get a fancy robe to boot!

I remember the first time I encountered the Thalmor, before I knew who they were, was a death squad. This was with a character I made a very long time ago. After that I got it into my head that I was supposed to attack them on sight. I later saw a group with a prisoner, killed the three Justiciers on site then realised I could let free the prisoner. This was with my first character before Missing in Action or Diplomatic Immunity. Did MIA later with that character and recognised them.

That was a long time ago, now I've come across Thalmor random encounters a few times since then with my newer characters. Death Squads, Thalmor with prisoners, random Thalmor, sometimes even a group of Justiciers fighting Stormcloak soldiers.

They all thought they were superior to me, maybe, but nothing they had was superior to my Pa's axe.

-be me wearing chestless fur armor and amulet of talos
-suddenly thallor attack
-yol... TOOR JULLLLLLL!

about never meeting the thalmor before, you actually see Elenwen in Helgen.

For the kill order thing, it's indeed weird they send pple to kill you before you do anything. I like to think maybe one of the bandit leaders I killed was selling them information on Talos cults.

It doesn't bother me much when they come for me thou. It's actually a good excuse for my characters to kill any of then on sight

I thought these encounters occurred only after reaching level 8, but also only after having committed some act in defiance of the Thalmor (attacking a patrol, freeing Thorald, infiltrating the Embassy, etc).