It's got to be painful to spend decades trying to scare people into believing that the opposition party wants to destroy the Constitution and take their rights only to put a guy in the office that happily says he wants to do just that.
I think I've mentioned this in the past, but I'll say it again here. One of the things people (especially the media) haven't figured out about Trump is that he approaches things very much like it's done in business. He sits in a meeting and tosses out ideas. He's willing to suggest just about anything as a possibility, then see what the response it, then make a decision.
This is very different than the typical politician who carefully crafts every word that might reach public ears. They wait until they've decided on a policy before ever mentioning it. This leads the media to do a lot of tea reading with regards to parsing the words that come out of politicians mouths, because they are so used to this ultra-cautious way of speaking.
I think he also likes to play devils advocate. He'll intentionally toss out a suggestion that he knows is a bad idea, and is something that (in at least a couple cases) are associated with the "other side". Then he'll wait for the condemnation, decide it's not a good idea, and then go and do something else. In this particular case, if he started off presenting the negatives associated with actively working to prevent people who "red flag" in some ways from having guns, he'd be accused of dragging his feet, or being the typical pro-gun guy defending crazy people with their guns. By tossing out the whole "let's not wait for due process", he puts the outrage in the other direction (OMG! You can't take away guns without due process, that's unconstitutional!), which allows him to appear to want to do what the people want, while realistically not actually giving them that because, well... let's face it, there's just about no way to do what many people are demanding without suspending due process to some (or a great) degree.
I've noticed that he will tend to be blunt with stuff like this. Totally propose the crazy idea that the mob seems to be yelling for, knowing it'll get this kind of negative response. Allows him to shut down that train of thought without appearing to be negative on the idea. I've seen this kind of tactic in business a few times, so I've recognized it. I've seen managers who will take the nuttiest idea in the room and appear to encourage it, allowing the team to figure out that it's really a bad idea, then sit down and figure out an actual good idea. It's actually a time saver, because if you just blow off the bad idea immediately (cause it's a bad idea), at least some folks in the room will still think it's great, or at the very least be upset that their idea didn't get any consideration, and keep trying to circle the conversation process back to that bad idea. This method nips it in the bud pretty much immediately, since even those who might otherwise think it *might* be a good idea, will go with the crowd and condemn it.
Kinda like what's going on right now, right? Last week, everyone was talking about how to proactively prevent people from having guns if we (who is we?) think they might do something "bad", with every possibility that any such action resulting from that line of thinking would require some significant infringement of due process. Now? We're all wailing about how you can't violate due process. OMG! It's like the guy's a freaking genius or something. No, he's not. He's just applying some pretty basic management techniques. Interestingly enough, they're techniques that most of the public has never seen, especially with regard to public policy.
Good job falling right into that though.