Marine Corps Air Ground Combat Center are primarily paper pushers. They are tactical air support. This might be a real disaster in the making. They are not trained in crowd control. Not to diminish their importance in a world dependent on computerization, they are experts in their field. But, the "Air Ground Combat Center" is not a combat unit.
This is not necessary.
The Posse Comitatus Act (PCA) doesn't allow for the Air Force to be involved. I am fairly sure the idea of a Marine Air Unit falls into the same danger in that this unit has contact with Marine Air Support. Helicopters, drones, etc. They need to be stopped. People are going to get hurt.
There is one other thing as to why now.
There is a nationwide movement of demonstrators set to carry out national opposition to the USA Army anniversary parade on Trump's birthday. It is called the "No Kings" movement. I believe the “Veteran’s for Peace”group is involved.
Trump will use that as an excuse to escalate a state of emergency and a Police State in more than simply California. I really don't care if the Army Anniversary coincides with the Insurrectionist President's birthday. The Army was in the USA first. Here again, Trump is doing something inflammatory to drive Americans over the brink.