Yeah, everything I've ever heard is that the reluctance is on their end, not Maryland's.
With them joining the AAC, plus their rivalry games with Army, Air Force and ND, it only leaves them with 1 game a season for scheduling themselves. And more often than not, they probably want that to be a game they can play on their home field (ND never plays in Annapolis and Army is always neutral site). They probably also want to avoid Power 5 schools for an opponent they have a greater likelihood of beating, for bowl eligibility.
In other words, I wouldn't expect to see Navy on the schedule anytime soon, unless they somehow get paired up in a bowl game, but even that is probably unlikely. The AAC and B1G currently don't have any bowl agreements that pit them head-to-head, so it would have to be a game where one or both is a fill-in for another conference.