This takes me back to the storm of 1987 and dealing with a dozen or more people who took an unauthorized absence because 'they physically couldn't get in'. Most were legite, though one person lived opposite the company!
In your case, It's unfair, but an employer will argue why your hubby didn't make an attempt to get to work through borrowing money from a friend, family member, contacting the DWP etc. Did he say in his meeting that he made various attempts to get the monies to get there?
There is no set time for BACS payments to be credited on a day (usually midnight to 2pm) . It is logical that even if the 30th had been pay day, that the monies wouldn't have been in by start of work.
Speaking as a former senior union member of the CPSA and taking everything into account, I would leave it and tell your husband to put it down to (an unfortunate) experience. Rocking the boat anymore in the current climate would be a big risk. They would know that you would not have the financial clout to represent yourself in a meaningful way. Treat his return to work as a new start and try to move on.