How would those who died in the War of 1812 react to football players not honoring the Star Spangled Banner, a song written about the flag some of them literally died to defend?
If there is an active FBI investigation, and the subject attempts to buy a gun and is denied because he or she is flagged, does that not alert the subject to the fact they are being investigated? What if the person is innocent? Would they have to prove their innocence in order to regain their second amendment rights? That's not how our system works. In out system, you are innocent until proven guilty.
Many politicians are fine with only minor changes to our gun laws in the name of public safety, but there are others who understand exactly why the second amendment exists and for them gun ownership is a problem. The difficulty for the average American is distinguishing between the two. How then do we know?
In the case of the Virginia reporter shootings, the gunman had undergone and passed a background check. He had no criminal record, and was never found psychologically unfit to possess a firearm.