There's a historical marker in Echo Canyon about this. It says, essentially, that the army was sent because they thought Utah was in rebellion, but Utah was not actually in rebellion, and therefore it was not right/legal to send the army, and therefore it was legitimate for Utah to resist the army. (It's in Utah, so no surprise, the historical marker is a Mormon-view spin on what happened.)

So, wait, let me make sure I've got this right. It's legitimate for you to fight the US army because you're not in rebellion? Um, hello? The moment you start fighting them, you're in armed rebellion!