I'm thinking from the human nature side of things even the most loyal of Trump's troops really don't like getting their daily rhythm and routines disrupted, especially on a regular day off from work. That's family time, Church day, getting soaked in brewskies, fishing time and wrenching on their beloved cars/trucks time. Well, jus' say'in I'd be personally pissed to have that one day off taken from me by some jerkoff draft dodger, even if by the contract I signed my life away on I'm supposedly on duty 24/7/365. My attitude for the day wouldn't be shall we say, very cooperative. Now say if it was family day back at the unit my spirits would be much more positive.
Perhaps.
A slightly different angle from my comments in the OP is to look at it as a "Trump Pride Parade". Pride parades are something that one largely does from a POV of love, and while there are Nazi Pride Parades too, I think in either case one has to be sufficiently 'out of the closet' for either event (respective closets, obv).
Take Greenman for example. Trump supporter? Absolutely. Willing to stand out in front of a crowd and basically shout, "I'M BIGOTED AND I'M PROUD!", no. He would have loved to have been there, sure, but not so much as to actually show up let alone be in such a parade.
There are enough Nazis around to be concerned about, but not nearly so many wanting to be out of the closet with it. For example, ICE agents with masks.
Maybe all of those who were "marching" in that parade were die-hard Trump supporters, but with that level of awkwardness that doesn't come from pride but something weaker (though with more resolve than those who didn't even show up), e.g. peer group pressure / feelings of obligation.