Well, Robert Morris isn't nobody in the lax world. They made the NCAA tournament (with an AQ from the Northeast Conference) in 2018 and 2019; in 2018 they lost their NCAA game to Maryland 14-11, which is not too shabby. The school is in the Pittsburgh suburbs, and they have been playing lax for 16 years or so.
They also have a decent basketball program and have been in the NCAA basketball tournament 8 times, including, most recently, 2015, when they lost pretty handily to the eventual champion (what was that team again?
) in the first round.
All that being said, perhaps RMU isn't that familiar an acronym. In sports, you will sometimes hear the school referred to as RoMo or BobbyMo.