Can somone explain this new NHRA rule?

[Unit 5302]

Looks to me like the NHRA is kicking back a little subsidy to helmet manufacturers.

Snell-90 is a very outdated snell standard. The "90" stands for 1990, and there have been numerous new standards adopted since then. Quite frankly, helmets do not retain 100% quality in absorption forever, and a 10-15 year old helmet, while better than nothing by a long ways, is overdue for replacement.