I think we’re agreeing? The entire premise of my comment is that trying to get clever with tube stacking injects more chaos and risk into an already chaotic and risky scenario.

EDIT: To clarify, in general I also agree with the point you seem to be making that guns are dangerous and trying to make them seem less so by loading so-called “less lethal” ammunition makes it easier for the user to forget that. But if somebody wants birdshot, they should at least just load the whole tube with birdshot and accept that their load has different ballistic properties than buckshot.