Don’t forget you have to get acceptance from the diversion airfield before you commence diversion.
What if your original destination is unavailable and you’ve held for 10 minutes waiting for the diversion airfield to accept you? Do you carry on holding? How long for?
Once you suspect you may land with less than 30 minutes fuel you must declare a Mayday and you can then divert with priority.(Mayday not Pan)
I imagine in the military, if you wish to divert you make the call and go immediately but in the commercial world a busy airfield might not have the capacity (or handling) to accept you.
The fact that it was the same airline may be down to the fact they are the largest operator there, no other reason and certainly not anything more sinister or foolhardy.