Agree with the consensus that a Mayday call was not required.....too little time, and unnecessary, in that of course it was a mayday ; A320 with no power and not much altitude? The pilot had said what the problem was most concisely.
Isolating the incident, by imposing RT silence or transferring non emergency traffic to another frequency is an ideal....but it may take time to set up....finding a body to do the work or a spare workstation are just two possible problems. Possibly a technique to employ with longer playing incidents.