Like it or not today's actions at the capitol building will be condemned by the media, establishment minded republicans, and the religious right. It doesn't matter that what happened is minor compared to months of rioting, looting, and murder by the left and BLM. It doesn't matter that election fraud claims were dismissed without hearings and audit requests were denied.
When Trump lost in November I realized immediately that it would be nearly impossible for the political right to gain Casus Belli, and the actions today, much like Charlottesville are going to be used to oppress right wing thought for years to come. It is likely that the establishment republicans are going to vote for gun control measures to put the right wing populists in their place, when normally they would not.
The media, local and state governments, big tech, and other corporations all gave them(selves) Casus belli for their "mostly peaceful" actions throughout 2020. The vast majority of people will believe those narratives, and now they have another one to war on right wing populists with. I don't see any positive path from here. To be fair, I didn't see any positive path before today either, but I hoped at least some uniparty republicans would be afraid to enact a far left agenda, not any more.
Casus Belli only exists in an honor society where strength punishes rule breaking. You just spent the entire first paragraph spelling out why that isn't the case for the political elite.
They didn't need good cause, everything up to now has given them cause to believe no-one is going to stop them no matter how shitty their justifications. All that's changed is you just realized the extent of oppression they were always going to reach once they decided they could ignore the will of the governed. If anything they have less cause to immediately go ahead with anything they want since they just got a very clear message they aren't quite untouchable yet. But everything up to now says they're going to try to change the untouchable part, rather than their behaviour and shitty justifications.
But if you want to talk about people who believe in honor and needed good cause to let things move to the next level: Steady, dependable, but peacemaking Americans, who didn't want violence of any form, the kind of people who would go organize and join volunteer clean up crews after their local businesses got burnt down but didn't approve of the idea of militia actually stopping the burning. Those people, especially the veterans, just got the message loud and clear now that an unarmed woman was executed in the capitol building at the first whiff of disobedience near the elite, rather than the permissive attitude everywhere else in the country. If people start taking things into their own hands, they're no longer going to stand in their way and say "stop, that's too far", now it's going to be "understandable, carry on", hell some of them might even be tempted to lend a hand.