I don't get why he tried to do it, really. Especially twice. It eventually only drew attention to himself as son of the candidate AND trying to vote without having been reggied (and VA does not have same-day vote for new registrants).
It's unclear to me what the kid was trying to do. Really vote for his dad, or just throw doubt on how Virginia monitors attempts to vote without proper credentials. And why would he do the latter if the kid wanted his dad to win? Whole thing becomes an infinity of smoke and mirrors...
"Look at me, I might even be a wannabe Democrat trying to vote against my Republican dad and so yeah it's true that the Dems are into fraud." ?!
There's a reference in the cited piece to the kid having said he had a friend who was 17 and was allowed to vote, but that was anecdotal, a comment by the kid to a reporter. If that had been tracked down and found true, all it would have done was land some hapless poll worker in the soup for having let someone underage reggie AND vote on the same day, and the vote would have been tossed.
As for any supposed support there on GOP fraud claims, it would be absurd on the face of it. In fact it points up the problem the GOP had with those occasional attempts to manufacture appearance of mass fraud during the 2020 presidential elections. Drawing attention to the fake fraud caused reporters to make the effort to verify, and since the whole point of the attempt was to draw attention anyway, there were breadcrumbs the size of pancakes leading back to the fabricator.