Wow...so you want psychotic, suicidal, depressed people to have the same access to guns as you because of "politics"?
The physician has to abide by the law, and the physician also has to abide by the Hippocratic Oath.
So they're not going to lie when they diagnose you...the only party in all of this that not only has the capacity to lie, but probably will, is the person submitting themselves to the examination.
And the only reason they would lie is if they knew they wouldn't pass the screening if they're being honest.