The gun-control lobby is attempting to use the San Bernardino shooting for political fodder. The problem is that the incident occurred in California, a state they consider to be a model laboratory for gun restrictions.
They've chosen to sidestep that issue, and they're proposing a new solution: bar anyone on a terrorist watchlist from owning firearms. If we don't look too closely, it seems sensible. It also makes for good soundbites about security.
In practice, it's a terrible idea, and it's something that should offend anyone interested in civil liberties.
Consider the "no fly" list. One has no way of knowing whether they're on it until they try to board a plane. If they are, it's nearly impossible to find out why they're on it. Aside from a feeble DHS program, there's no way to redress the situation. Even that venue places the burden of proof on the accused.
It also bears mentioning that neither Farook or Malik were on the list.
It's troubling enough that such a system is used to interfere with air travel. If it's used to strip enumerated rights without due process, it becomes something much worse. Of course, gun-control advocates aren't letting that slow them down. Consider Senator Dianne Feinstein's feelings on the situation:
(…) only individuals who are charged and convicted of a crime should be denied a firearm. That would be a critical mistake.
This is what comes of the "just do something" mentality. It really has nothing to do with public safety–this is about getting a gun law, any gun law, passed while they can rely on public outrage. Any rights trampled in the process are collateral damage.
…which is pretty much how we got the no-fly list in the first place.