I think they meant it in the way that if you want to own a gun now or in the future, you shouldn't seek mental health help. And now, as hacks can reveal the data to your employer/school/in laws, there can be discrimination from that angle as well. That was their point I think.
It doesn't help, he's saying that losing the ability to own a gun is a disincentive to seeking professional help.
Well yes, having a basic and fundamental liberty restricted without harming others is a tremendous disincentive.
I don’t know of any mental health diagnosis that can bar someone from owning a gun in the US.
Even if you receive inpatient treatment, as long as you went voluntarily, doesn’t change that.
You could do a simple check to find out what your don't know: