We, unfortunately, do not have that sensor, but we discovered through some investigation that we could monitor (trial and error) after we lost one of our birds that the chickens just will NOT move once it's dark. If they happen to be in the way of the door, then that door will come down on them. That's a fact - just try to move one of your birds in the dark with a red light on (they can't see red light). They resist the push to move because they can't see.
We ran through the scenarios over and over with our doors and came up with the same solution over and over - the door must go down in the light. I'm sure our chickens thought we'd lost our minds, but it has worked now for about 4 years. If one of them is in the doorway, and we have a few that like to park themselves there on the way in at dusk, they get the message once that door starts to move! The door comes down, and they have about 10 minutes to find their spot for the night. Once all are in, we come behind them and do a head count.
I don't understand exactly how the IR sensor works to stop the door, but I definitely sense that you're on the right track to changing how it functions. In the end, the one thing we found that worked was making sure that door went down when there was plenty of light. Once the door is closed, then we have timers extinguishing the lights...
So sorry to hear about your rooster too! It's a horrible way to lose a member of the chicken family, but things do happen, and we learn from them for better or worse...
The IR sensor is like the "safety eyes" on most garage door openers. They shoot a beam across the opening and will prevent the door from closing (or will cause it to reverse direction) if something breaks the beam. My problem was the standard bracket height - which is ideal for chickens that are standing or walking through the opening - was too high to detect just their flattened out necks as they lay across the threshold. It was the confluence of events that lead to the perfect storm. I've never seen any of my girls nap ON the threshold. If they'd been awake, they most certainly would have moved. I'm tempted to post the video as you can see the rest of the girls on the perches startled and were very attentive to the door noise. Unfortunately for Brownie, she must have been sleeping a bit too deep...