STFU unless you've done FEA impact analysis on the RMR's housing. Their patent is legit and based on sound engineering.
See also "STFU unless you've been through the patent process."
With nearly 10 million granted to date, yeah, it's getting a bit tougher to find room for a new patent, but the whole process of triangulating within the "whitespace" of existing IP is a well-known defensive strategy. I've seen some real shit granted approval by the USPTO, but ignore it at one's own risk. Willful infringement carries a penalty of treble damages, and that'll add up quickly.
I strongly suspect that Trijicon and Holosun have already talked, and that this is a tactic by Trijicon to utilize its leverage to move things along. The argument will likely be settled out of court, if for no other reason it'd be suicide for Holosun to go up against the legal team of a much larger company.
Like it or not, this is the way the system works, and I for one am happy to live in a country where there is still some basic respect for the concept of intellectual property.
EDIT: having read the patent supposedly in question (8443541) over this morning's breakfast, this has nothing to do with "the shape of a housing" (which wild likely be covered by a design patent, not a utility filing). I'm not an expert in this space and some of the claims look overly broad upon initial glance, but the devil is in the details.
Also, everyone reading this message will now get a bill from me for providing this expert opinion.