Joseph- You seem convinced that there are poskim that paskin that you absolutely need to get drunk to be yotzei ad delo yada, and that the Rama’s and M”B’s suggestion is not a halachically valid option. According to that premise, I agree with your conclusion that dina demalchusa dina/illegality of underage drinking plays no role in this discussion and the only concern is whether its dangerous or not.
I just disagree with your premise that there are any poskim today who rule that way and I believe that everyone agrees that at least bedieved you are yotzei if you follow the Rama’s and M”B’s suggestion.
We agree to disagree.