On meta those flags go straight to moderators. On main sites they go to the queue first but eventually go to moderators if the community doesn't handle them. On most sites "eventually" means after 15 minutes and on a few it means after an hour. Even if meta sites had this review queue and even if the higher limit were used, my guess is that most of those flags would go to moderators anyway -- most people don't check meta nearly as frequently as they check main and meta has a smaller active population to begin with. Further, in my experience as a mod on several sites, flags on meta are much more rare than flags on main. Putting all that together, it's really not worth creating (and encouraging use of) another review queue on per-site metas for these relatively-rare flags.
It might be a good idea to find a place (maybe in the mod-specific help? maybe in the flag UI?) to remind moderators that they shouldn't expect the community to handle these flags on meta. On some of my sites, mods pretty much ignore new NAA flags to encourage the community to handle things directly. There's no point in doing that on meta; the community can't handle them.