In a civil trial, Brady would have to turn over his records and his refusal to testify can be used as an inference of his culpability. The finding was not based so much on the gauges, but the behavior of those involved. You can argue about the gauges all you want, it's not going to change the decision, nor should it. The proceeding was more in the nature of an administrative proceeding, which typically gives the accuser the advantage, but it is what it is.
The Patriots' pr people have been working overtime on this and many are buying it. When you put yourself in a hole, stop digging.