Same attitude that caused the problem in the first place, I suspect.
He must surely have realised the pressure was slightly below par - at the very least borderline - at the time, but his pig-headed attitude prevented him from owning up, thinking instead he could get away with it.
He seems equally reluctant to treat it as serious even now.
When will twits like this realise they'd earn far more respect if they just owned up and said 'look, it's borderline, I'm not happy with this - I'm going to make certain it's comfortably in the safe area...'
And continuing to bury his head in the sand leaves you with even less confidence in his manner and ability.
Bottom line, it looks like he's putting his fragile ego before your safety and convenience. Lousy attitude, lousy service. He's an arshhh.
After this is resolved, I think you have a responsibility to report him to Corgi (at least), and anyone else with an interest.