"The evil" is official = must be used.
Anyone demanding something be used because its "official" is the problem.
According to what Lanefan set up in his point... the convention's DM is presenting a sheet of house-rules that MUST be used in the game he is running.
And there is no difference between a DM presenting a sheet of house rules that his game is using because he made up a bunch of things himself... versus the DM presenting a sheet of house rules that his game is using because he downloaded the official D&D errata.
Sure, bill91 is right in that the amount of changes on that sheet might be greater if taken straight from the D&D errata... but odds-are... 95% of those changes will never be used, read or see the light of day (and quite possibly already edited out of the house-rule document if the convention DM actually presented one to players.)