Other than the “The idea that Bricker is pushing” part, I agree with you.
But Bricker is pushing something well beyond that. In post 83 of the GD thread, Bricker concurred with the second paragraph below:
Bricker’s thesis that the Dems implicitly made a commitment for all time to not threaten gun rights, and that their having ever changed their mind violated that commitment.
I agree that a good number of Dems did, for a period of years, signal that they weren’t going to try to encroach on gun rights. What Bricker needs to supply substantiation for is the purportedly eternal nature of that implicit commitment. That’s well beyond any popular meme.