In this case apparently no hull damage or missing doors , why divert to Limoges , Gerona wasn't far away and flight could have been continued unpressurised.
btbag, probably because the enroute Safety Altitude exceeds 10,000 ft (I would have to check but I think it's in excess of 12,000 ft) and the pax oxy system has a maximum endurance of about 15 minutes.
From all the evidence it's seems the decision to divert to Limoges was sound.