Come on, FDOS, not trying to be clever but trying to keep this into proportion and maybe introduce a touch of humour. An EU ruling? Insurance claim, fine and a bit of spleen vented, certainly…….
Words fail me; someone’s (expensive) holiday potentially ruined and you feel that you are the arbitrator of proportion?
As it happens, there is an ‘EU Ruling’ (to use your incorrect terminology) that covers airline baggage, it is EC889/2002, but unfortunately it will not assist the OP’s son with this delay.
Insurance would cover the damage or loss to the skis, nothing will restore the lost enjoyment that the OP’s son suffers from not having his own skis available.
I guess one cannot learn empathy.