That advice is more appropriate for any would-be jackbooted thugs, than it is for patriotic, law-abiding American citizens, of which there are 90 million who are armed.
If the federales could somehow press all of the armed services personnel and every law enforcement officer in the country into confiscation duty, they wouldn't amount to more than about 5 million strong.
Even the most arrogant dictator would shrink from those odds.
Further incrementalism is their only choice, and they'd better be exceedingly careful as to what they say and do while they're at it. They're about two inches away from sparking something that they do not have the power to extinguish.
Unfortunately, Obama is a psychopath (I mean that in the true clinical sense of the term). His arrogance is not the problem per se, it is only one manifestation of his pathology. We can't assume that logic and a reasonable grasp of the situation will guide his actions in a practical direction.
IOW, we can't base any expectations of his behaviour on rational reasoning processes. This man's mental illness means we have a very loose cannon here. We should not assume that any action by him is without the realm of possibility.