So you don't see a problem with denying a person his protected rights without due process?
The person filing the petition doesn't need any proof but his opinion, cops and judges are not psychiatrists.
If you're going to claim a person is a danger to himself you need proof in the form of a mental health evaluation by a professional not the opinion of some Joe Schmoe
One, no one is being denied due process. If the resulting investigation proves that the person is harmless, they get their gun back and the matter is closed. They are not arrested or held: they just have to hand over their gun until the investigation has been concluded.
Two, judges are not going to just willy-nilly automatically order confiscation in response to all such petitions. They are going to question the persons who filed them. They are going to consider the credibility of each petition. In the case of petitions filed by police officers, I would certainly hope that judges would take those very seriously, and well they should.
Three, you don't have to be a psychiatrist to recognize when someone is disturbed and might pose a threat to themselves or others. Look at all the warning signs of the shooter in the Parkland shooting. The guy was obviously disturbed, and if this law had been in effect in FL at the time, the tragedy might have been averted.
Four, when we have school kids getting shot up at a disturbing rate by disturbed persons, I am very willing to err on the side of caution, to be safe rather than sorry.