Incidental contact. No legal guarding position so unlikely to be a player control foul. Definitely entitled to the spot as he got there first and is not extending his space to create contact.
Just like the slashing driver that careens off the side of a couple set players on the way to the hoop who may wind up on his butt, no foul on the defense for simply occupying a spot, and player control unlikely.
The contact created a travel? Tough luck--that may teach him to stay in his own space. Send the ball the other way and tell the coach to sit down and shut up (nicely and properly, of course
)