NRA-ILA | NRA Wins Victory as Congress Reverses Obama's Social Security Gun Grab

WOOHOO- so now all of those people are going to get their guns back, right? What do they do, go to H&R Block when they file their taxes, sign up for rapid refund, then get a voucher to go to the gun store? Moral is, the government needs to make this right A.S.A.P. it was an illegal gun grab!
JS
S/F

Only two questions remain -
Once this is done, how long will it be before the VA is out of our gun cabinets?
Are they (the government) going to properly compensate those individuals that have had their property stolen?

I have been following this for the last couple days. While driving I typically listen to NPR in the morning to get me fired up and conservative talk radio at the end of the day to find out what Trump has done to piss of liberals. I fully expected NPR to talk about Congress shooting down a gun control bill that prevents the mentally ill from owning firearms without talking about the Constitutionality of it. What I did not expect was conservative radio talking points, while praising the decision, said that the bill was set to keep the mentally ill (people that are not mentally capable of handling their own affairs) from owning firearms. They did not go into details of why this was unconstitutional. On face value is seems like a common sense move and has been a box on the 4473. As responsible gun owners we don't want the mentally ill having guns. They are the ones that commit mass murders and set off anti gunners on a fit of calling for gun grabs.

I know I am missing something on this. Can somebody help me to understand why this was a bad law?