This quote from the piece caught my eye -
"But Republican lawmakers argued that the regulation reinforced negative stereotypes that people with mental disorders are dangerous."
I would argue that this is not actually true.
People with mental disorders are not, be default, dangerous, no argument there.
However, people with mental disorders and guns, are obviously dangerous, it takes no brains whatsoever to see that.
This is not about de-stigmatising the mentally ill by allowing them to have guns, it is about pandering to the right-wing voters who empower Republican Senators and the President, to ensure that such empowerment can be guaranteed going forward.
As to the second part of your OP - I think the Trump regime is only interested in dismantling the aspects of Obama's legislation that either disadvantages right-wing voters and business owners, or legislation that those same groups simply don't like.
I could respect - if obviously not agree with this naked pandering to the all-powerful NRA, if it were not dressed up in some seriously flawed nonsense about empowering mental ill citizens, when the only empowerment that are receiving is an addition set of opportunities to kill other citizens, or get themselves killed.
If that's President Trump's idea of 'forward thinking' - he'd better hope that none of the newly empowered mentally deficient citizens decides maybe he should not be around to do any more damage.