The Real World said:Should some fan choose to vent his frustrations with the team, let him. It doesn't make him any less of a fan than anyone of you.
The guy stood at the tunnel and booed his own team's seniors leaving the field after a heartbreaking loss. It's incomprehensible and it could easily be a lot of other things, including grounds for institutionalization, but at an absolute minimum it really does make him much, much less of a fan than anyone else in the entire world who wasn't standing there booing their own seniors.