They didn’t announce it to him in advance, and he’s not a coward. There will be a response to this.
The governor can assemble raid parties against ANY federal facility in Florida, seize federal land and offices. The Federal government has no exemption from state law enforcement arrest and jailing. The Sheriff can send them all packing by enforcing the Constitution. The federal government is an agent of the state; is subordinate to the state governor and its legislature; and CANNOT usurp the governors authority.