No, the crew did not necessarily over react. I'm sure they did what they were trained to do. The over-reaction was on the ground.
In one of my previous lives I did Air Traffic Control:
If an aircraft declared a PAN our reaction was "OK, we've got a problem"
If an aircraft declared a MAYDAY then "Holy Sh1t" and people would run around with heads up butts.
In this instance, it seems, the crew declared a MAYDAY and people on the ground ran around with heads up butts inconveniencing all users of the M1 motorway in the process.
So why the criticism of the authorities on the ground when it was the aircraft commander that instigated any over-reaction?