Even if that were true, you have to give them credit for saying "No! I'm not gonna hide what I think, because that's for cowards, and I will kill any man or elf who says otherwise!"
I see arguments for both sides really.
As do I. I sympathize with the Stormcloaks' cause, as do all of my Legion characters. I completely understand why they'd want to be free of the Empire, but the thing that they don't seem to realize is that the only way to beat the Thalmor is together, not apart. My Bosmer character, for example, is a huge supporter of the Legion. He's also a devout follower of Talos, wears an Amulet of Talos at all times, and attacks every Thalmor agent he sees.
Spoiler And it isn't just my characters, either. At the end of the Legion questline, when Ulfric dies, Legate Rikke quietly says "Talos guide you."
All in all, though I can see why the Stormcloaks want to be free, all it would do is make the Thalmor all the more powerful.