The 'unsolicited evidence' (proving MoD knew of the risk of over-tightening before 1990, and of the mitigation that eliminated it altogether), was provided to the judge, HSE and Lincolnshire Police. MoD had denied knowing of this at any time to 2011. The charge and judgement were based on this false premise.
As she said, the judge chose not to read it, but passed it to the HSE for comment - specifically asking about disclosure of evidence. (MoD had denied the existence of the QinetiQ report that formed the bulk of this 'unsolicited evidence', and had even briefed Philip Dunne MP to say in Parliament that MoD knew nothing of the alleged content).
The HSE replied (and this is in writing) that the evidence (of innocence) was irrelevant, although of course they didn't say 'of innocence'.
Thus, the judge was seriously misled (by omission), and many of her remarks are tainted by not having read, or been advised by HSE of, this exculpatory evidence.
In furtherance of their stated strategy of not upsetting MoD, it would appear (again, HSE's statement) that Martin-Baker concurred. Plainly, the company didn't think it irrelevant, but chose not to use it in their defence. That is, they took the hit.
The judge's remarks make if clear (at least to me) that she understood something was very wrong here, and she makes a point of criticising the fact that vital evidence was not put to her, due to the guilty plea. However, it was, but she didn't read it.