Just a tad of back ground.
In America we have separation of of states rights from Federal government rights. In this case the states have enacted rules, laws regarding helmet use and the voters have over ruled them. That pi$$es them off so they go to the feds and ask to use highway tax money grants for specific uses that are not in the original federal guidelines for all vehicles, not for motorcycles only to force a national helmet law.
The insurance industry is behind all most all directions the National Highway Safety folks go. When the industry wanted to limit "super bikes" to 600cc some states balked so it could not be the rule of the entire country. In this case the states wont all line up behind a single type of helmet for all or even all age riders.
If states want to pass laws against motorcycles, bicycles, trikes, scooters then let them and if their voters don't care so be it but use state money to do it. But to create false, mis leading spin reports to get the federal government to use highway tax fund money to single out one form of vehicle from all others is not how our government is supposed to work.
I am not against helmet laws but they are a states right to pass. If you don't like a certain state law, lobby against it to get it changed by the voters or move your fanny to some other state but quit asking that all of your wants, desires, beliefs and fads be enacted by the feds on every one else who might not agree.
Why do you think there is such a difference between California and the rest of the country as regards laws of all types? Oh and New York State is the state that got caught using this grants to pay lobbyists to push for helmet laws nation wide, they also are fighting in the courts their use of these grants to fund motorcycle only traffic stops. If you like that then live there. If not live in one of the other 49 states. That is how our government was meant to work.