Earlier quoted context omitted.
I'm curious - what are those reasons, and how would the lack of an invitation thwart them?
Most obviously, if you invite the military in and ask them to secure a portion of the building, you're exposed to the risk that the commander-in-chief will order them out (or order them to stand aside); it's unlikely that forces could be redeployed fast enough to respond to such a defection. (And no, you can't avoid this danger by having all the forces working together everywhere; far too many command-and-control iss…
Let's do a thought experiment: let's say there are a few elements in the police who are active QAnon believers, sprinkled in at various levels. Let's also assume some more force members are not believers, per se, but sympathize with the cause, and are willing to look aside since they may dislike some legislators who they see as enabling BLM, Antifa and other un-American actors (in their eyes) and believe that something "weird" happened with the elections and/or the whole establishment is dirty. Would these individuals not listen to the orders of the commander in chief, even when not delivered via the official chain of command?