I think the only rationale is that the leaders of Army and Navy refused to submit to the lack of leadership being exhibited by the rest of the PL when it comes to dealing with athletics. I imagine they just said something like this: "We're playing. Athletics are important, and we think a modest OOC schedule can be done safely. It's silly for other schools to tell us what to do when we know a lot more about our situation than outsiders do."
I think Army and Navy would be willing to leave the PL, if necessary, rather than be dictated to in an area that really is none of the PL's business.