Is it possible that the SBMing that exists in the matchmaker can be re-tuned to simply prioritize game experience (aka Spartan Rank) over Skill measurements?Even if it was possible, I don't think it would be a good idea to try to match firefight players with other players around their own SR, because then new players would never win and higher ranked players would easily win 100% of the time (I'm not necessarily assuming you thought it was a good idea. You may have been asking out of pure curiosity. I just felt the need to point that out). If anything, it would have to do the opposite of what it does in PvP, and try to make teams with the widest possible difference of high and low ranked players. Warzone Firefight currently has a lot of problems but I don't think the matchmaking is really one of them, or at least a big one.
Actually I was thinking it could look to diversify the team as much as possible in Heroic (a good mix of highly experienced players, middle, and low), look to pair very highly experience players with low in Legendary while looking to group the middle. I assume Mythic is mostly made up of middle and highly experienced players.
Another thought went past simply a players total Spartan Rank as a measurement of experience, but perhaps an invisible measurement of playlist experience too which I assumed is tracked by the SBMMing system. That could also have some influence in WZFF if it was allowed to.