In the legal philosophical sense definitely. It is however possible that the state laws are wrong. But if indeed that is so, the states themselves can come to that judgement. It isnt as if the Congress were uniquely qualified to make the determination - and its possible that states might properly allow cities to enforce 21 while 18 is allowed in more open spaces.
Drinking isn’t a constitutionally protected right, so it is legal to those under 21 from drinking.
It can be argued (not by me) that since long guns can be purchased by 18 year olds, their second amendment rights are not being denied.
It must also be pointed out that it is not illegal for 18-20 year olds to possess a handgun, they just cannot purchase one from an FFL. FTF sales or gifts are OK.
I recently called AMICA about getting a quote on renters insurance. One of the questions they asked me was if I had guns in my residence. I refused to answer the question.
I decided not to go with AMICA but instead stay with my current insurer.
Yep - old enough to vote and fight should equate to old enough to anything else.