These guardsmen were ordered to deploy against America

No, they were ordered to deploy in America, and ordered to protect federal buildings and "maintain order". There's nothing illegal about that order, or treasonous about following it. They've been used that way plenty of times before. Generally when they're deployed following a natural disaster, one of the things they're there fore is to deter looting. The whole "natural disaster" bit seems the main thing that the National Guard does these days. Then there are other times where they're deployed to maintain law and order: the 1992 LA riots, the 1968 riots after the assassination of MLK, etc.

There's nothing treasonous about that. And the orders authorizing those deployments aren't illegal orders. If you were one of the racists who wanted to attack MLK's march from Selma to Montgomery, you might have felt that the national guard preventing you from attacking the marchers were "race traitors" or evil, but history would have shown you were wrong.

In this case, history will probably show that the guard stood around looking tough, maybe made a few arrests. Some of those arrests will historically be seen as violating the first amendment, but some will be seen as normal, boring legitimate arrests. There will probably be some protesters beaten up, but that's almost certainly going to be the cops rather than the national guard.

Maybe, at some point, an order will come down to load live ammunition and start shooting protesters. If that happens the soldiers who follow those orders might be considered "evil", but I imagine many won't follow that order because they'll see that as stepping over the line.

Also, you really need to read up on the actual definition of treason.