The was I understand it is they will only be allowed on paved roads. I believe the thought behind it is because Utah allows them on city streets they should be allowed to be driven in National Parks..State Parks allow them..I can't see hauling a UTV to Zion to drive the same road I'm driving my car on..But as we are all aware some people are crazy..The article probably does gloss over details. I can't speak with absolute authority but what I think is the case is that Utah allows ATVs and UTVs that meet certain criteria to get a license plate and registration similar to any other street-legal motorcycle.
Utah has a list of requirements like reflectors, lights, horn, muffler, blinkers, speedometer, windshield and they have to carry insurance as well. So it would be those I presume to be the OHVs being discussed, not just any random OHV.
I've experienced my share of hooligans and renters in UTVs and personally don't have a particularly high regard for them but if a street-legal dirt bike is OK on White Rim then I see the logical argument that a street-legal UTVs should also.