"I guess he has no problem making edits to his articles when people other than Andrew Hussie have a problem...?"

Changing your wording slightly to make it less abrasive is not the same as being asked to retract a work that you still stand by and were explicitly told that you would not need to worry about.

"That's not an unreasonable ask..."

It is not. The problem is not that Hussie asked that the articles be retracted.

"...and it also doesn't seem like it's some grand betrayal if that wasn't made obvious from the start as negotiations became more serious."

It is. Hussie's opinion of these articles seems to be constant and negative. Entering negotiations without being honest about what you want (and, in fact, directly lying about it) is slimy at absolute best. Later presenting the change as though it is not a change at all is even slimier. This was one of the central questions about Gio's involvement. It should have been brought up at the beginning, and they should have been honest about it when Gio brought it up.

Homestuck has all of the power in this negotiation. They are the ones who hold the rights to half of what Gio was hosting, and they have more money and more lawyers to enforce their will. Consequently, they should be held to a higher standard of conduct.