As a point of clarification, a snowmobile does not meet the legal definition of a watercraft, even if an attempt is made to operate as one. Therefore boating regulations like wake, speed and registration do not apply.
It is illegal in NH to knowingly operate a snowmobile across open water.
215-C:7 Operation on Open Water Prohibited. – No person shall knowingly operate a snowmobile on open water, also known as skimming. In this section, "open water'' means any area of an inland water body that is free of ice and snow. This section shall not apply to events as permitted pursuant to RSA 215-C:50.
Finally, depending on circumstances authorities can bring additional pertinent charges. In this case the charge of Reckless Conduct (RSA 631:3) was brought, which is a misdemeanor offense.
Separately, the second skimmer has also now been arrested. And as this news account reveals, a thorough multiagency investigation led to the issuance of a complaint & warrant that resulted in arrest. Sorry, there was no "conspiracy" or "favors" being tendered here, as needlessly speculated above. Just another case of the wheels of justice making their necessary, albeit it sometimes slow, turns!
The story of the second arrest can be read at the Citizen
HERE...