It's all about context. For many years this forum was infested with united fans masquerading as City fans. I'm talking of some posters with thousands of posts btw. It may sound a little preposterous to someone from the outside, but it was a real issue, especially in the period after the takeover, and was most pronounced after a loss, although its much less prevalent these days for obvious reasons. To appreciate the veracity of this assertion you have to understand the nature of the relationship between City and united fans and their assumption that they would always be able to mock their neighbours mercilessly. It's the same mindset that thought it was acceptable to place a banner at a prominent position in their ground mocking their local rivals for fifteen or so years.
The preponderance of united fans on here stirring shit is why that poster as been rounded on, as much as anything he's done himself. It's plain to me, however, that he's an Arsenal fan.