This was brought up once before but the only thing I found to do as an Admin was two different ways to make it so whenever I pushed to speak in game in the server it auto muted everyone else till I took my finger off the button. You need a client side config file with the binds to make it happen...also to avoid spamming the chat box with me muting and unmuting everyone I just edited the print to chat out in the basecomm and recompiled it.
I have to update that file and redo it every so often if its updated by the SM team but either way it works pretty good.