There are about 35 million Americans ages 10 to 17. Giving them the vote would transform our political conversation. It would introduce the voice we're sorely missing -- a call to stewardship, of governing for the long run, via the kind of simple, "childlike" questions that never get asked today.
Letting alone the likely real manipulative intent of the suggestion, this is not likely to actually have a real impact on political discount rates. The average inheritance is currently $90,000, but lifetime income transfers from parents far outstrip this figure, and it is important to note, as "The Role of Intergenerational Transfers in Aggregate Capital Accumulation" (Kotlikoff and Summers, 1981) do, that the bulk of the $3.884 billion of U.S. wealth holdings in the U.S. in 1974 are accumulated intergenerational transfers.
Parents are currently transferring a their preferred amount to children. Let us imagine, for the sake of the author's argument, that children do not care about parents at all, while parents clearly care about their children, to the tune of a significant portion of their lifetime wealth. Furthermore, money is fungible. The decision to give children the vote is, by the author's point, equivalent to giving them a small transfer of wealth, which will have no impact on the total wealth they will be given, it simply changes the form in which they receive it.
To illustrate the point, let us say that a child is receiving $1,000 in lifetime wealth from their parent. Their parent also makes political decisions that cost the child $100. Giving the child the vote is equivalent to forcing the parent to transfer $100 in cash--they will simply transfer $900 in other cash and $100 in forced transfer, rather than $1000 in other cash.
Corrections suggests that altruism is so strongly present in parents that an interior solution is inevitable. The only feasible argument (one the author did not make) is one of public goods and private transfers.