He flees because he is a hired hand and cares nothing for the sheep.
13. The hireling fleeth. The reason is, because he careth not for the sheep, which means, that his heart is not moved by the scattering of the flock, because he thinks that it does not at all belong to him.
The Pharisees claimed to be the church's true pastors and treated Christ as an intruder with no commission from them. But His doubled amen, Amen, amen, stamps this teaching with absolute weight: whoever does not enter by the gate but climbs another way is a thief and robber, bent on mischief and damage to the flock.
AI summary
Commenting on John 10:1-18
The hireling fleeth, because he is an hireling,.... And has no propriety in the sheep; had he, he would abide by them, and defend them; but because he has not, he will not expose himself to any danger, but leaves them: and careth not for the sheep; what becomes of them, providing only for his own safety.