And, the petition in question was for Buffalo to wear them for the rest of this year, not next year.
The rule is that you can wear throwbacks for two scheduled games, and that either:
1) Because Tampa Bay chose to wear away unis in their home game vs. Buffalo, Buffalo
was given permission to wear the throwbacks there and not have it count as thier second game, or,
2) The Tampa game was Buffalo's second scheduled throwback game and Buffalo has petitioned the league again, only this time to wear them a third time for the Denver game, and got it.
Either way, I believe Buffalo is wearing them against Denver.