Many "model" disciplinary procedures based on ACAS advice will include the following as a guideline of the sorts of thing that constitutes Gross Misconduct (ie something that may result in summary dismissal
"Refusal to carry out a reasonable management instruction" or "failure to follow a management instruction" and bla, bla.
So if its true that a Captain instructed said martyr to comply with Uniform Standards and said Martyr refused, it's a fairly direct correlation with a dismissal for Gross Misconduct.