Is this so unreasonable?
There is nothing in the original Constitution guaranteeing the right to vote. Likely because most white men weren’t allowed to vote (naturally most, if not all, black men, Asian men, Indian men, and women weren’t allowed to vote either). Generally the franchise went to those who could vote in elections in Britain, which is to say to educated property owning white men belonging to the established church and over 21 years of age. The 2nd Amendment further restricted it by excluding anyone who was not in the militia. Ideally voting should be restricted to those who are capable of selecting effective and honest politicians. Of course restrictions on the franchise are highly unlikely to be adopted, since anyone who would be dropped from the elctorate would strongly oppose their removal.