Ball Hit on Opposing Side

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A coach asked me about a call from last weekend's tournament:

The opposing team had just completed their 3rd hit, and the ball was falling close to the net, but had not yet crossed the plane. Her blocker clearly went across the plane of the net to get it (with both hands above the height of the net). There was clear "wrist action" and her player in her words, "put the ball down".

She was called for illegally crossing the plane. The R1 told the coach that her player had "attacked" the ball, which is illegal. His determination was that the although the other team had already had their 3rd hit, the ball was attacked and not blocked.

After looking up the rule (9.6.4) it does appear that a block after the 3rd hit is legal before it crosses the plane and that wrist action (9.5.1c) is an acceptable part of a block. My question is this, how do you differentiate between a block and an attack in the situation above? It doesn't seem to match any of the attacks listed in the rule book: spike, tip, dump, or overhead pass.