[Arito]

I'd make him call and explain the situation to him. The alternative is to go against the rules and apparently wishes of another player which is worse than abiding by the rules and telling the inexperienced player he has to call because that's what he said initially. Most of the time they don't mind either.

I do think WE1 is a douchebag if the player really is that inexperienced.

So if I'm:

WE1: I let his all-in stand
E1: I probably don't care either way. I will explain it to the inexperienced player if the host lets the call stand or I will try to convince the WE1 to just let his all-in count (if the host rules that the all-in counts).
Host and friend: I let the call stand, because any friend of mine is going to understand the situation if I explain it to him.