Yes it does, however, after I upgraded to the newest version and then set the bluetooth coexistence mode to enable, I was able to make calls over UMA with my bluetooth headset enabled.
I even tested just before I upgraded to the latest version and with a reboot on the old FW, both tries dropped the call and kicked over to EDGE.
I did an update without resetting back to factory defaults, but did make a backup of my settings just in case, and after the FW update and config change to the coexistence setting, I could make UMA calls with my bluetooth headset.
So even if it's listed that way in the white paper, remember the makers of dd-wrt added what ever adaptation they could or knew how to. The paper didn't cover the specifics of how to code it and such.