i have lots of solid arguments that show that christopher is wearing a wire at the time of his death.
my proof:

in his final scene, like in his first scene he is wearing a hat. only this time it has a wire in it. remember the only other time a character wore a ballcap on the sopranos? yup, Jack Massarone in the "MOST" or Museam of Science and Trucking hat provided by the FBI. We know they eventually whack Massaronne but never indicate that they caught on to the "hat trick". With CM it's a Clever hat of course.

why did CM shot JT in the first place. because he at that moment realized that was totally alone. the only person who ever related to him was adriana and thanks to him she was dead.

Remember when Adriana told him that she was talking to the feds? she confided in him because she was stuck and he actually looked like he might flip then. and he was actually considering it. remember when he goes to the gas station and while he's fueling up his $60,000 Hummer he watches a poor family getting into the crappy car? at that moment he decides to not flip but to instead go to tony and sell out adriana. He changed his mind and she died. Later in JT's apartment, he regrets this.

At the time he goes to see JT that night Adriana is dead, he is totally alienated from Tony and the rest of the "family", JT and their supposedly profound AA relationship is all he has left for comfort. he talks seriously about flipping. when he realizes that even the JT relationship is lost to him too he knows he is all alone. it goes through his mind about what a huge mistake he made the first time. Once again he decides that he will flip and pay everyone back. but this time to ensure that he doesn't sober up and change his mind, he kills JT. He knows that killing a well known associate and civilian will result in a murder rap which will force him to flip or fry. He removes his own option to change his mind.

and where was the blowback for jt's murder? tony would have been super pissed when he found out. apparently he never found out. how can this be? the mysterious cold-blooded murder of a hollywood screenwriter with mob connections (Clever) didn't make the news? it must have been covered up then. by who? we see CM leave the scene. he just walks out. remember when tony killed ralph? all the precautions they took? of course the cops covered it up as part of the christopher flipping deal.

by the way, notice how the car flips in the accident? almost taking tony down? obvious symbolism.

after the wreck CM tells tony that he needs to get a cab because he's on drugs and if afraid he'l lose his license. do you really think CM is afraid of losing a drivers license? especially when he must know he needs an ambulance? especially again when you consider that CM would never voluntarily tell Tony that he's on drugs unless he was trying to cover up something even worse! What could be worse? Remember the beating tony gave him after he got high after Adriannas death. No, what he's afraid of his that tony may see the paramedics find the wire.

Why was CM high the night of the accident anyway? because he couldn't deal with the guilt and shame of what he was doing.