I agree that it was a well labeled prank. However, how many people even look at the url? I didn't until I saw the “it was a prank” message. Also, how many people look at the banner? Would you notice if I switched the forum banner here?
As for the likely response by runners and the response by the BAA, I agree that we have too much of an entitlement culture. That said, I don't blame the BAA at all for protecting their image. Image is everything. Did they have to get lawyers involved? We don't know what happened behind the scenes so it's hard to say. Did the BAA ask nicely and get rebuffed?
Whatever the case, as I already ststed, image is everything. This wouldn't be the first time a prank by a third party was blamed on the target of the prank by its potential customers and the target suffered as a result. While I'm sure the prankster didn't mean harm, the potential for harm existed and the BAA has the right to protect its image and prevent or minimize the potential harm.