Pace, look, we most likely will never know what made him do that. Ironbutt delivers a scenario that might have played a role.
I made my boss spill his coffee on a G/A recently - we had to good a climb rate for the atcos taste and got a lower altitude as we were zooming upwards. In order not to bust the altitude given, well, I leveled not as smooth as I wished to.
Boss was furious, shirt was dirty...
Next very next flight (next day) we went to a smaller island and just after touchdown we realized a flock of seagulls sitting on the rwy. The decision NOT to G/A but to brake hard (I was PM on this leg) was surely made partly due to the drama we had the day before. (no issue, the Sovereign brakes are sooo good...)
I know my boss for 20+ years, we do not have a punishment culture and we are certainly not in master/slave relation. Never the less the boss would throw another drama, just to let remaining steam off...
These things play a role in the subconscious part of our brain. Sometimes more than we think.
However, at this point any scenario is as good as the other...