At a practical level on the hoarding - what can the president do, declare martial law? There aren't enough police/solidiers to enforce it anyway. Far better to get to work on the source of the panic, especially if you believe it can be contained if you prioritize that.
It's clear we're behind on testing - and definitely the FDA is owed some blame. But at the same time, if the tests don't exist in quantity, they don't exist. That takes time - and be all accounts, they seem to be working hard on getting there.
It doesn’t take more than a few very visible examples to clamp down on that kind of behavior.
It is absolutely the job of a president, at least a good one anyway, to ask the populace to chill the fuck out and stop hoarding toilet paper and medial supplies.
And quite frankly a real smart leader would have started testing the fuck out every person with a pulse. More understanding of how many people have it is important.