So on the offsetting penalty call early in the game, they had an ineligibly receiver down field, and we had a pass interference call. I am not seeing how those offset if the initial pass was "illegal" wouldn't that trump the pass interference seeing as how it happened before the pass?
Your point makes sense, but this is how the rules work. I guess it's to prevent the defense from realizing there's going to be a penalty on the offense, so they commit PI or something which results in an interception. The rule works the same the other way around though. Say the defense is offsides, the offense can still be called for holding or offensive PI which would cause the penalties to offset.