Silver, ATC probably ask for the POB because they are required to.
As for the rest, ATC's reaction was prompted by the chaotic radio calls and lack of information provided by the crew. The crew would have done this in the sim every 6 months for years. To blurt out a panicked "we need to turn" without giving a direction is mind-boggling. No wonder ATC thought the situation was dire and that they might need an immediate reland. What about "Mayday Mayday Mayday, UAXXXX, engine fire, tracking direct Zimmr until advised, standby for further information".
As for the fire bell still ringing during the radio calls...