under ICAO procedures an engine fire requires a Mayday call.
I think you'll find the commander still gets that decision - unless you can quote the document.
Not disputing the actual decision in any way, mind.
Re the "check wheels" comment - there is a thread on R&N about a CRJ landing flapless, in which the pilots forgot to lower the gear (
and didn't complete the checklist, and failed to notice the continuing warnings) - one of the suggestions on the topic was for ATC to issue and automatic "Check Wheels" to any PAN or MAYDAY aircraft, which wouldn't be a bad thing IMHO.