The BCS rankings did not cherry pick individual polls. It used over ten polls and rankings to determine the top two in a system that everyone agreed on before the season. Including USC.
USC, like all DIV I schools, agreed to play under the BCS system. When they didn't win under that system (that they agreed to), they claimed and accepted the AP title. The very next year, they won the actual BCS title. I didn't see them declining that one and calling themselves the AP champ. If the AP wants to crown their champion, that's on them. If USC want to claim AP title, that's also on them. But there was not a co-national champ in the 2003 season. There was the BCS champion (LSU) and the beautiful crystal football and there was USC and whatever trophy they got.
Simple fact of the matter is that the BCS worked as well as a flawed system could have. I really believe most of the piers that be looked at it as a stepping stone to what we now have. Anyway I look at it as a tremendous improvement to what we had beforehand and am glad that it was voted in when it was. LSU was the true champion of 2003 as we were the BCS champion, if USC wants to claim the AP title that is fine but not relevant to the started goal of every team that suited up that year. This new system will be even better than the BCS however it likely won't be any less controversial in many of the seasons a their will likely be a many as 6 or 7 teams which would have an argument to be in the top four.And I firmly believe these arguments have been the biggest driving force as to the popularity of cfb for more then two decades. Fans arguing over the internet during the offseason keeps CFB in the forefront year round which evidently increases fanaticism, passion & interest.
Your definition of "accepted" and mine are different. I see a lot of air between Les' hand and the football. He was definitely "holding" the crystal football.