Well, what level was the paladin (and rest of group).
We can be scared of big nasty things that can squash us like a bug on a windscreen and if we cannot win, it might be best to run?
The natural instinct of an animal that finds itself in a no-win event, should be to run...
A paladin that perceives the best part of valour (honour) is to retreat to fight another day is wise.
And I think they were very considerate to write on door a warning to others?!
Still, as a player who feels betrayed by such an event due to lack of motivation from rest of team might pray the gods (like Xathoqqua) for some kind of revenge? But seriously PC do die and running from a Medusa is no shame, still perhaps they could return with a stone to flesh potion, but that should be rare.
Perhaps just have his twin brother (if player is willing) who is a scout and has exact same attribute have a premonition of events and have him approach the group to have then rescue his brother...?
Still, ignore any of above suggestion as they might be wrong, but worth a laugh?!?