Yes, it's ridiculous. They should really only grade-skip in math after giving the student take-home exercises during the current year that will serve as a replacement for the skipped grade. It's irresponsible to do otherwise, imo.
1) Allow the child to go at their natural pace.
2) Grade skip every 2 years, with take-home exercises.
3) Grade skip every 2 years, without take-home exercises.
4) Force the child to go at the same pace as the rest of their same-age peers.
That was my biggest problem, that and I wasn't actually on-board for the skip. Educators need to learn how to admit when they fucked up and learn how to improvise a new strategy.