That's the point though. Ulfrics entire rebellion is part of the thalmor plan it's supposed to make you feel like he's right and you should help him and demonize the empire so people will turn against the empire thus unknowingly aiding the thalmor. Ulfric isn't a 'former' thalmor agent he IS a thalmor agent. Elenwyn(The ambassador to skyrim) Is the very same person who interrogated(And eventually broke) him.The thalmor are simply staying 'hands off' so as not to compromise the delicate situation(It would obviously ruin ulfric if he were seen getting help from the thalmor while fighting to 'free skyrim'....from them.) You can find that out as soon as you get to the embassy quest and read the thalmor's dossier on him.
The same dossier that says he is an uncooperative asset. You're cherrypicking.
When you ask Jarl Ingrod about the Thalmor at their little embassy soiree, she says "people lie by what they say and lie by what they don't say- these (i.e. the Thalmor) are talented at both." If people would listen and think a bit, they wouldn't take the dossier at face value.
The empire are the ones who are cooperating with the Thalmor- not secretly, but openly. They're letting the Thalmor kidnap and torture imperial citizens who are suspected of being Stormcloaks.
Second. Ulfric spits on tradition by declaring himself high king without even having the support of most of the other jarls. The moot is the only way to declare a high king which means the other jarls need to agree.
He says this is because the empire has been choosing jarls for decades, so the deck is stacked. Your argument is highly ironic if you consider how much the imperials respect Nord traditions by trying to declare Ulfric a murderer, even executing the man who let him out of the gate. They don't even respect their own laws (the executions at Helgen without a trial), let alone Nord traditions.
Instead he just claims the title and simply assumes the other jarls will 'eventually' agree with him.....even though his army is lacking in size and the people are still divided. He declares skyrim 'for the nords' despite that he apparently 'invited' the dark elves to windhelm then promptly ignored them and left them to rot in the cities slums. Which were even renamed to the gray quarter(because of the dark elf skin color). It's clear Ulfric puts on whatever face he thinks will benefit him at the point in time. He is not anything near the honorable man holding up skyrims traditions they make him out to be.
The Dunmer have been in Windhelm for 150 years. Letting people who pay no taxes and owe you no fealty to take up a quarter inside the walls of a fortified city is a
massive boon in a medievalesque world. I really don't want to hear any more bleeding heart crap about the poor Dunmer. If people had played previous games or read up on the lore, they would know how funny it is to argue from the standpoint of racism against Dunmer.
Ulfric does not assume the jarls will simply agree with him. He argues with Galmar that they need time and convincing because they have families to consider. Legate Rikke says that more come over to Ulfric's side every day.
When hammerfell chose to break from the empire it was allowed to do so.
The empire tried to force Hammerfell to cede their lands and the Redguard said "hell no". That wasn't a friendly bargain.
Skyrim could have done the same but Ulfric killed the only person with the authority to declare such.
Which Torygg would never have done. He and Elisif embody the term milk-drinking lapdog. Even if it's true that Torygg supported Ulfric's ideas, he obviously never voiced his support, let alone actually act on it.
Fourth- What everyone overlooks is that the banning of talos worshipp was a term of the peace treaty.....so when that peace ends it's likely talos worhship will begin again, the empire was never really enforcing the ban until it became apparent they weren't and that's when the thalmor began excercising their rights granted by the treaty to seek out talos worshippers(and at the same time spy on the empire obviously) essentially Ulfric gave them everything they needed not just to hurt the empire but skyrim as well and is in fact a traitor to both.
And yet the empire is also producing propaganda saying Talos was never divine. The Thalmor started interfering in Skyrim after the empire promised Ulfric and his men they could worship Talos freely if they retook Markarth.
The Thalmor have no "rights." They only have what power the empire grants them, by constantly tucking tail whenever the justicars wag a finger at them.