The right to carry guns openly is not absolute, and it never has been.
Try getting on a plane with a gun if you think open carry laws have no limits. Or going to a concert. Or going to a sports game. Or try taking a tour of the White House with your AK-47, lol.
There are, and always have been, recognized gun-free zones... whether you think this is right or not, it is reality.
The Governor is within his legal rights to declare a state of emergency.
The timing (Martin Luther King Day), location (same place there was a fatally violent White Power rally), and intended presence of out of state militia groups all add up to legitimate concerns for public safety. Plus, it is probable that Northam has information from law enforcement that he is acting on.
You gun nuts need to step up or step down here. Either prove you are law abiding citizen, like you so vehemently and constantly declare, and ABIDE THE LAW...
Or refuse to obey the law, engage in a firefight with local law enforcement, prove yourselves to be violent anarchists, and see how quickly national opinion slams against militia groups.