Having looked at the exhibit/chart detailing the specifics of the claim, Trijicon asserts Holosun infringes because: 1) the Holosun products are optical sights; 2) with two posts extending from the base; 3) some glass supported by the posts; and 4) with a red dot projected onto the glass.
That covers literally every open emitter design out there, to include some that pre-date the RMR. My non-patent law expertise opinion is that the patent seems incredibly broad, and I'm curious how that can stand.