Basically, one encounter was ridiculously easy (three first level wizards try to go melee versus six second level optimized melee characters, and all they had prepped was Magic Missile which wouldn't kill a single hero if they all dealt max damage to the same target). Since the player characters were bulldozing through the module already, he made a small change by modifying their spell loadout to Sleep, Charm Person, and Ray of Enfeeblement to make the encounter more challenging. The players did indeed find it more challenging and memorable and although the PCs won, the dice were hot on the DM side and two player characters were killed.
After the game, Noah had this discussion with the RPGA regional coordinator (modified from his retelling for clarity):
RPGA Regional Coordinator: Some of the players told me that two of them died.
Noah: Yeah, there was this one encounter with mages and they died in that fight.
RC: But...no...that shouldn't happen.
N: What do you mean?
RC: Players aren't supposed to...well, what am I trying to say?...Those adventures are balanced so that players can finish them.
N: Yeah, but I found it was a little too easy. The spell loadout and three wizards...
RC: That's as it was written. Did you play it as it was written?
N: Well, I changed the spell loadouts for the wizards because they sucked and it's not logically what wizards would take. They weren't even ridiculous spells; every Wizard has Sleep.
RC: But...you changed it? You can't change it.
N: Oh...well, sorry.
RC: No, you don't understand. Do you know how upset players get when their characters die?
N: But that's D&D. Characters are at risk of dying.
RC: But not in the RPGA.
N: When characters die, players are upset, but that's how the cookie crumbles. You know, play smart and you won't die, but sometimes shit happens, it's how the dice come down.
RC: We can't have that. We can't have you killing characters.
N: I didn't go down there trying to kill player characters...I just set up an encounter—that really was stacked against the bad guys—and that's how the dice came down. I wasn't really being unfair here, the adventure said they were trying to kill them, it said they were trying to secure the prisoner, and that's what I did, I sent two guys to take care of the only guy who was standing and the other guy was trying to free the prisoners.
RC: We can't have you DMing games if you are going to be killing player characters.
And ultimately they did ban Noah from DMing games in the RPGA. It was his belief that this was unfair, especially as a consequence for something as simple as changing three first level wizards' spells. That said, the RPGA coordinator seemed to be more upset that his changes made the encounter potentially lethal and did indeed kill two PCs.
While I understand that this happened back in the AD&D era and the regional coordinator doesn't represent the RPGA as a whole, I'd like to know: is Noah's experience typical of the RPGA, either in the past or in its modern form? Can a DM be banned from the RPGA for making the module more lethal, especially if they kill player characters?