OK folks, think about this for a minute. The legal precedent has already been set in this area concerning closing roads crossing private property. Lower Helldorado was lost because no one could prove use more than a handfull of years back. Moab Rim trail has been in constant use for at least 40 years, more than enough to prevent it's closure. Grand County & the local Chamber of Commerce also have a vested interest in keeping the trail open, it was one of the original Jeep Safari trails.
Now look at the financial aspect, TNC has been trying to raise money for this purchase for nearly 6 months & still has less than half of what they need. That doesn't sound like an organization that will be able to afford to pay the legal costs of trying to close a well established road that the county claims. They'll be damned lucky to get the rest of the money together in the next month to finalize the purchase.
As long as there isn't a major problem with off route vehicular travel across the section that crosses the property in question, there won't be any effort by anyone to close the road. It won't make any difference to anyone who truely cares about keeping Moab trails open, because those people will stay on the designated route.