I got the ranger away from the BOS bunker and they accepted me inside, but Elder Macnamara refuses to move from his spot in front of the BOS flag and the two mark V turrets, so I can't progress any farther, because I can't talk to him in the control room.

got the same problem, unforntunatly no sallution, have been trying to get the guy thrown off the elder post, but seems that quest gets stuck too because the geezer won't move.