How would you call this??

[AndrewMcCarthy]

A does not hinder himself- the defender was between A and the ball. B interferes A’s opportunity to move toward the ball while making no attempt to get to the pass himself. It's DPI.

You can say that B has every right to run down the field, whether he knows where the ball is or not, but ONLY IF he doesn't interfere with an eligible opponent’s opportunity to move toward, catch or bat the pass.

In this case he interferes. Flag down.