To be fair, they may not have known about the deal for his return. It sounded like a lot folks were new to the guild and didn't know Eddie.

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

From my understanding the raiders were new and never known Eddie and about the deal that was made. The guild members had a right to be upset if that information was not told to them and he should have never been made raid leader to new raiders, now if the original raiders were still there it might have work.

OK, thats kinda how I understand it, that they didnt know. Yes, they are the new guys and you could say "Hey, I made this deal before you even came in", but then again, they have become members of the guild now and members of the raiding team, and I think it would have been only fair to TELL them about the deal, as IMO they did deserve to know that.

"This was discussed to the interim and would not be a problem."

The interim leader did know about Eddie and that when he returned he would take over again. That in itself makes the interim leader's actions even more immature, as those were the terms he had agreed to when he took over as leader.

"So yesterday, everything hit the fan. I got attacked by one of the guild members (an officer no less) because they felt that Eddie didn't deserve to be raid leader when he gets done with the raid team. I tried to explain why and he ignored anything I said and just kept praising the interim."

The other raiders may not have known originally that Eddie would be taking over again if they were new, but it sounds like once the issue came up the writer attempted to explain the arrangement but the people complaining wouldn't hear anything about it. Regardless of whether they knew or not, they still acted very childishly and in a way that almost assured it would end badly and that no decision that everyone could be happy with would be reached.

Therinor,

Both the interim and the raiders knew. Some were actually told that their position in the raid was conditional until Eddie's return. At least 3 weeks before the major blow up, they were told that eventually Eddie would come back. This was told to them when people in the raid had been disrespecting officers, and I had a meeting to discuss the issues with people's attitudes towards other raiders.

Sounds like this guild has a recruitment issue; no current members had been there long enough to remember 'Eddie'; the raiders don't recognise the officers as having authority; only show loyalty to their immediate raid team.

Either the guild is only recruiting unpleasant people or there is a problem with management failing to get raiders to feel invested in the guild.