Exactly... they might not have known!
The thing is: Did the raid team and the interim leader know that Eddie was supposed to get his spot back eventually?
Because seriously, if I was in that situation, taking over, hopefully growing into my new role, doing my duty, only to be told "OK, now the other guy is back now, and I promised...", I would be a bit disappointed too.
Sure, you can choose to say "Its my guild, and when I make a deal like that, its my decision and they just have to deal with it", but I will have to deal with the consequences, as not everyone will roll with those punches.

Raiding together for quite some time will usually make you grow together... you become a team, maybe a group of friends, and then stuff like this happens, maybe totally surprising to some, its no surprise they stick together.

I do agree also that the way the other members handled it wasnt very mature (then again, we only heard one side of the story, but then again, maybe I am just bitter), but once again, imagine you grow together as a raid team, and then te GL goes "Oh by the way, I made a deal with this guy last year, so yeah, he he, and oh, if he uses harsh language, sorry if that offends you, he doesnt mean it in a bad way"
Question is: Did they all know about the deal? Were they told this and maybe reminded of it in between? Because if they didnt know, its no surprise they reacted negatively, no matter in what manner, but thats just my opinion