mcm3312

I've been playing with vision, looking at hu plo spots where the flop goes XX. Our opponent leads the turn on a flush draw board and we call. On the river the flush misses and he bets.
Sometimes it PREFERS us to block the most of the missed flush draw cards as possible to call. My hypothesis is that in these spots he will start his bluffing with hands that have no flush blockers. But then sometimes its the complete opposite.

CAN SOMEONE HELP ME WRAP MY HEAD AROUND WHY??

EX)
622hh xx. Qx 2/3 c. Tx b100 and our hand is AQ43.

When we have Ah and another heart we always call
When we have 3 hearts we call a little less
When we have just one heart we mosty fold
When we have Ah we basically always fold
When we have no hearts we always fold

Why would blocking hearts be good here when there arent any other natural high freq turn bluffs?