While it was probably a bad decision by the boat, it could have been the bridge operator screwing up. Years ago I saw a bascule bridge lower onto the upper bridge of a pusher tug crushing it. The tug had signaled for the opening and was the only boat going under the bridge. I believe drugs were found to be a factor.
A couple of years ago we were waiting for a bridge to open. We had waited an unusually long time, several sailboats had accumulated. The bridge finally opened, we all started to go through, then the bridge started to lower with some boats still heading under the bridge. The boat I was on was getting a tow, we managed to get the attention of the boat towing us, who wasn't aware of the danger
, and started to turn away, another person on our boat had the presence of mind to sound 5 shorts. The bridge stopped, went back up and let the rest of the boats through. Never found out what happened.
If the bridge attendant had a reason to close the bridge before all the traffic was through the bridge would have sounded 5 shorts. I have seen this properly done when boats were strung out far enough and the bridge had been open long enough that it was time to close for awhile.