The ATV rider did not have the entire right lane.

But he had space to go around the police vehicle. In the news video posted in this thread, the captain stated that the officer at the scene gave the ATV driver enough space to pass him, butt the ATV driver could not change lanes fast enough to avoid the police vehicle.

Moreover, the ATV driver had enough distance to stop before making impact with the police vehicle.

The police vehicle had its lights on. A police vehicle with flashing lights is pretty easy to see. I can't think of anything on that trail that would have been easier to see. And yet the ATV could not stop in time or turn to avoid the police vehicle.

The image shows how far the ATV is from the police vehicle when the police vehicle starts blocking the lane. The police officer saw the ATV before that point. Surely, the ATV driver would have seen the police vehicle with flashing lights at the same time or earlier.

That's at least a football field away. The ATV should have been able to stop or avoid colliding with the police vehicle within that distance.

Instead, the ATV driver does not appear to have reduced his speed significantly before running into the police vehicle. He hits the police vehicle at a dangerous speed.

Perhaps the ATV driver would have seen the cyclists and pedestrians in time to avoid them. Perhaps he could have slowed sufficiently to stop or avoid them. Perhaps not. The video of the ATV driver's reactions after the police vehicle pulled into his lane at 100 yards away strongly suggests that the cyclists and pedestrians were at great risk from this ATV driver.

If the ATV driver could not see or avoid the flashing lights police vehicle at 100 yards, how is he going to see or avoid the cyclists and pedestrians? The police vehicle was not blocking both lanes, and yet the ATV driver did not even control the ATV enough to go into the other lane.

The police officer had a choice to make. Block the ATV at a distance at which the ATV should have been able easily to stop before making contact with the police vehicle or take the risk that the ATV would have collided with a cyclist or pedestrian.

I think the police officer made a reasonable decision given the time constraints. The video of the ATV driver's reactions to the police vehicle at a distance of 100 yards suggests that the police officer made a reasonable decision.