Why do pros patrol workers when trying to block buildings?

The best example is trying to block a zerg early hatchery. Most pros will set their worker to patrol in a small area to block the hatchery. Why not hold position or just "stop"?

Solution 1:

Patrolling keeps the worker from getting killed easily, while still blocking the area.

And it's more efficient than manually moving around, you can let it 'patrol' and move on with your business.

Solution 2:

Patrolling the worker also prevents it from showing up as idle. This way, any idle workers that are selected can actually be used for something else.

Solution 3:

I assumed that the patrol gets the probe up to speed, so that they don't need to accelerate for further movements, such as the little way needed to move the probe to perfect position when building the expand. I might be wrong though.