He cut it too short....He should have added much more info defining "constraint" such as registration, age, felons...
But he does that with every topic...It's his FORM of oratory....and non-commitment.
I did not watch the debate but I agree with your statement - he cut it too short. But then again, it is the fault of the moderators not to press him on anything. The statement standing by itself and read broadly can find people agreeing on a majority of the statement. Would you want a truly insane person to legally have a firearm? Considering this day and age, I would recommend a class or classes of firearm safety courses. You could even CLEP it if you want too. There are people out there who can better teach the instructors of gun safety courses while there are others who would shoot themselves in the foot if given the chance.
But the main point is you are correct - these leftists never explain their initial statements and nobody presses them on it. And they never go to forums where people would press them on it.