Oh? Those taken away in the middle of the night, the Redguard who struggle and resist, the Stormcloak and the Colovian who fight over Skyrim? The Concordat was not altered when first proposed.
Hence why it was rejected the first time, however, once the enemy was faced, and the consequences known to The Empire, they made a strategic choice that saved every province in The Empire with the exception of Hammerfell.
Granted, it probably wasn't the best decision in the long run, but I don't blame people for choosing peace instead of war, specially a war that could've lasted for decades, it's one thing to kick the Aldmeri Dominion out of Hammerfell, it's a very very VERY different thing to take the fight to Summerset Isles (after conquering Elsweyr and Valenwood) and defeating them there, and that was something that after The Great War
no one could've done.
Many believe they could still fight. If Nord fighters wished to trade death and horrors amongst Elf types, who is Ozan to disagree? The true irony is the war was turning before the Concordat was signed. The Colovian failed to maintain his tenacity, choosing to allow victory to those who've plotted and stole.
What if I don't want to fight ? Why should I be dragged into a massacre ? Just because some backwards Talos-loving barbarian is itching to sate his bloodlust ? What about those that can't fight ? What about the soldiers who had just taken The Imperial City in a battle against all odds ? How was this war going to be won ? Who has going to lend the soldiers and resources necessary to take it through half of Tamriel to the doorstep of The Thalmor in the Summerset Isles ?
On a separate note, it bothers Ozan... no soul viewed them as a threat? Why? The Aldmeri dominion claimed Valenwood and Elsweyr for themselves and the Colovian allowed this and never suspected the Elf type to take more? The Colovian didn't think to strengthen their borders against a rising nation?
Obviously, The Empire was careless as a whole at some points, many attribute this to the decay of the courts in Cyrodiil, or the lack of a ruling Septim on the throne, regardless, I don't think anyone else could've fared better, The Thalmor played their move very well with the hidden camps in Elsweyr, their attack and strategy was swift and staggering, they were not an easy enemy.
Regardless, how does this benefit the Stormcloak argument ? How is a naturally exclusive, insular army under a banner of race and tradition supposed to save Tamriel from the Thalmor threat ?
I mean, if this was not a videogame, and there wasn't "an obligation" to satisfy the player who chose other than The Empire, then the stormcloaks wouldn't stand
a single chance against The Thalmor (I speak as if upcoming DLC was meant to resolve this).
Perhaps those who look upon the Stormcloak see a disruption of the status quo. Perhaps they see deceit. But Ozan sees men getting executed and he hears the dead were made so because one man challenged another to a duel and won. If he had lost, would the High King be a murderer?
The Stormcloaks don't execute people ? That's something to ponder, and something we can't deny simply because there's no direct evidence of it, maybe they don't publicly execute people as often as The Legion does, but they sure don't care about people who disagree with their cause, as Galmar Stone-Fist so well puts it.
As for the duel part, it's irrelevant, the High King would've acted in self-defense, since he had not instigated any attack, however, Ulfric admits to knowing his shouting put him in a position not of advantage, but of assured success,
he knew the Thu'um was powerful enough to kill Torygg, and that's why it's murder, he walked right through Solitude with the intention of leaving a corpse in the city's court.