I was wondering when this was going to start...
The question now will be what is the definition of someone who isn't mentally fit to own a firearm according to the laws already on the books. I can only assume they will be trying to uncover every nook and cranny to ensure as many people fall into that category as possible.
Surprisingly, this started a long time ago and this policy already affects over 100,000 vets (since 1999, so this isn't an Obama thing).
It's all tied to the VA's Fiduciary assignment process. If the VA makes the determination that a disabled veteran is not capable of managing the financial benefits coming from the VA, the VA requires them to have a fiduciary. That determination then gets forwarded for inclusion into the NICS due to the individual being "mentally defective".
The original intent, to protect the financial interests of the VA and the veteran, is not so bad, but the inclusion in NICS doesn't make much sense....without some legal adjudication. I'm sure a large portion of that 100K actually are batshit crazy or seriously lacking in mental capacity due to injury/mental illness, but they should at least have the ruling validated by a court of law.
There have been several attempts over the years to get that part removed, or at least require a court determination, but all have failed.