The full judgement makes very depressing reading
"In evidence, the first respondent gave the impression that the timing of his admission was purely as a result of the rate of progress of the Cabinet Office inquiry. In our opinion however, the first respondent’s approach to the inquiry was at best disingenuous, at worst evasive and self-serving. We consider that he could and should have been straightforward and candid in his response to the inquiry. That would have been likely to reveal his involvement in the leak at some time prior to the election, so that his constituents, when voting, would have been “in full possession of the facts during the election” (in the third petitioner’s words, transcript 9 November 2015 page 20). It is our opinion that his failure to be straightforward and candid with the inquiry resulted from his hope that he would not be identified as being involved in the leak – preferably not identified at all, but at least not identified until after the election on 7 May 2015, as otherwise his chances of electoral success might be prejudicially affected."
So effectively he did blatantly lie, so that his election votes wouldn't be affected, but it isn't against the law. I'm sure he will be out at the next election, if he doesn't have the sense to stand down.
I just hope the petitioners get the money they need to pay for this, and don't lose their houses...