Yes sounds like a delay because pax should be disembarked with the minimum of delay. Green threat? no, aircraft do not need to divert for this. Prestwick was the correct airfield to land at and an F3 escort is the best cause of action as 'you never know!!'
If Ryanair and the Irish govt don't like the way it was handled then don't operate in the UK. They are an Irish airline and are an overseas carrier when it comes to UK emergency planning.
Im sure the Irish authorities would have acted just as fast??????
SL