re: NOW I’m wondering if I should start buying enough for a few weeks - DoD related

Military operates by different rules. Just like you have to have a leave chit approved before you go on leave or some commands you have to have approval to travel so many miles from home without leave or special request chit.

After 9/11 we were told to stay in town by the phone in case you get called back in to work.

In a situation like this, you're still in the military, still being paid, and still owned by the government. They can tell you to do whatever they want you to do. This is fully expected.

They're doing this more as a precautionary measure than anything else. Our unit has one confirmed case already and besides, this domestic travel ban is only in place until May 11.
Local travel is still being authorized, but other domestic travel is only authorized for mission essential, determined humanitarian reasons, and warranted due to extreme hardship.

This virus is very contagious, and every time they get into formation they raise the possibility of spreading this.

Personally I think the travel ban is a bit much, at least domestically. There are obvious hotspots of this virus, place a ban on those locations.