The only reason hotac is not offered is when the reason falls under weather or 'force majeure' i.e nature or acts of god!
Apparently they were advised the aircraft was stuck in Prague thus it was an "act of god".
I'd understand this excuse if the act of god impacted this sector but not previous ones.
Anyone know what conditions at the airfield were like in Prague today, it's currently giving light snow, mist and a somewhat contaminated runway from the snow.