RFNOMNT, like everything in Plan 9, was put in because someone needed to use it, not as a purely academic exercise in adding features. It's behavior is what it is because that was necessary to get the job done. All the pie-in-the-sky "gee it would be nice if it worked like this, not that I'm actually using it" talk is unproductive. The "let's submit a patch and fix it" talk is scary.
Russ