Where exactly did the OP own up to his keeping an Oscar in a 55, as being a mistake, and that now he knows better? I must have missed that part. Not only did he not state that it was a mistake, he referenced several "care sheets" cough-cough, the first one on his list containing the following: Your Oscar aquarium should provide at least 30 gallons of space (about 114 liters) per Oscar, plus any space needed for any other fish. A minimum fish tank size of 40 gallons (about 152 liters) is recommended if you are keeping an Oscar.
While out of the other side of his mouth he seemed quite supportive of the fact that it could be done, and he knows, because he did it. In his initial comment he stated: A 55 will work. Which was followed by: I've seen it work before and it will work in most cases.
None of that is in the past, nor is that the OP admitting that he was wrong, or owning up to a mistake. My guess is that the majority here that are crying foul, and using the dramatic "pitch forks & stoning" critique never even glanced at the care sheets that the OP posted here, if not to support his comment, then for what purpose?
Even Frank, Mr. I Hate Care Sheets So Much I Recently Started A Thread on the Subject, apparently missed all of that. They were posted to support his initial comment, that being - A 55 will work.
There's those reading comprehension skills at work again .....