@elrjames777,
First, most of the shipments made by Floyd were not to Federal garrisons, but to state armories. As Grant noted in his memoirs, both small arms and heavy artillery were therefore ready at hand to be seized when secession had taken place. Fortunately, Buchanan was able to rescind the orders to ship ordnance to Galveston and to Ship Island before the shipments were actually made. Second, Article One, Section Eight gives Congress the power to provide for arming the militia--Congress gave President Washington the power (and by extension, all subsequent presidents) to establish and regulate arsenals in the United States. Congress did not give any authority for arsenals to the Secretary of War, it was given to the president.
Floyd was indicted for conspiracy and fraud. I haven't said that he was charged for the shipments. I also haven't said that he was tried--he was not, the indictment was quashed.
Your expression "even if militias had attempted" implies that they didn't, which is false. I'm not going to repeat my work, but i've already linked a page from a University in Florida showing that so-called state troops of Alabama and Florida seized some federal facilities, and attempted to seize Forts Barrancas and McRae at Pensacola. I use the term so-called state troops because that is what the states of Alabama, Florida and South Carolina called the troops--many of them militia members, although not exclusively so--which they used to seize or attempt to seize federal property. Article One, Section Ten, reads, in its entirety:
No State shall enter into any Treaty, Alliance, or Confederation; grant Letters of Marque and Reprisal; coin Money; emit Bills of Credit; make any Thing but gold and silver Coin a Tender in Payment of Debts; pass any Bill of Attainder, ex post facto Law, or Law impairing the Obligation of Contracts, or grant any Title of Nobility.
No State shall, without the Consent of the Congress, lay any Imposts or Duties on Imports or Exports, except what may be absolutely necessary for executing it's inspection Laws: and the net Produce of all Duties and Imposts, laid by any State on Imports or Exports, shall be for the Use of the Treasury of the United States; and all such Laws shall be subject to the Revision and Controul of the Congress.
No State shall, without the Consent of Congress, lay any duty of Tonnage, keep Troops, or Ships of War in time of Peace, enter into any Agreement or Compact with another State, or with a foreign Power, or engage in War, unless actually invaded, or in such imminent Danger as will not admit of delay.
Congress had not authorized Alabama, Florida or South Carolina to keep troops in time of peace. Those states did indeed sanction keeping troops in time of peace. The subsequent establishment of the Confederate States (a clear violation of Article One, Section Ten) is clear evidence that those states met at Montgomery, Alabama, intended to act upon a basis of unconstitutional sovereignty.
It appears to me that you don't know as much as you seem to want to suggest that you do.