Moving Screen? (Block)

[wyo96]

Freshman Girls. In transition, A1 is outside the 3 point arc, top left guarded by B1. A2 transitions into high post FT line with defender B2 between her and the basket. A1 gets around B1 and is driving to the basket. A2, facing A1 the whole time, slides down the lane with hands out for a pass all the way to the bottom block, but the slide prevents B2 from getting around her for help side D. A1 makes a lay up.

I did not judge the intention of A2 to prevent B2 from helping, so I passed on it. Coach B disagreed.

It happened twice in the course of 2 minutes and I passed both times. The post player has a right to move down the lane, but can she block the defender? There are several times a defender may want to get past a post player to help, and I have called block when the post player was clearly hindering the defender.

Thoughts? Thanks.