Teamsters and several safety organizations have challenged the new HOS rules. It won’t keep them from going into effect; but it will point out that the new rules directly contradict previous findings of the FMCSA.
I’ve been waiting for such challenges. The HOS rules were negotiated with lots of deliberation a couple of years ago, and they represent losses of rights for employee truckers. Independent Owner-Operators may have a different view, since they are playing with their own money and time, and might prefer longer hours even if it is less safe.
Like not wearing a mask.