While the defensive part of this treaty appears to have been ignore it's worth remembering the MHA has worked hard with other parties to try and avoid this war and to get across how foolish it was. We were ignored. Were not even given the required period of notice for an offensive action, despite talks apparently having been officially ended with enough time to do so.
Now I'm not saying that that clause is as important as the mutual defense clause, but for how long does MHA try and help and advise NPO only to be ignored, disrespected and kept in the dark? How long does MHA put up with being brushed aside and offended only to then be expected to come running when NPO goes against advice and starts some trouble? Friendship is a two-way process not just take, take, take.