Hold on there. It was said awkwardly—there is only one president at a time—but the sentiment is spot on. Of the people who have a shot at becoming POTUS in 2020, Trump is the most supportive of the 2A. There is not a Democrat who has a shot at it who is even neutral on gun control. The next election, for anyone supportive of gun rights, is a trade-off between anti-gun zealots and Trump, for all his faults, real amd imagined. In terms of gun control, the choice is between someone who abused his power as president to ban bump stocks vs someone who would surely abuse his or her power to ban guns.
I've seen a few names of republicans mentioned that might consider primarying Trump in 2020. Names like Krystol, Flake, and Kasich. Does anyone think those guys would have gone to the mattresses defending bumpstocks? We already know where any democrat would have stood. (Though if one of them had been president, maybe the republicans would have resisted a little bit more just because of partisanship...but not guaranteed). None of the likely 2020 victors will likely seek to roll back anything. We'll be lucky if they don't roll over on UBCs or a federal red flag law.
Sadly, there is no viable alternative.