No, I have not changed my opinion. While I listened to the theories and considered possible paternity, I was never sold on it.
I have always thought he tried to play "double agent" and perhaps was torn about what to do but still helped his sister.
I do NOT forget this statement from a "source":
According to WESH 2, a source close to the investigation said, "We kind of treat him separately. He knows what he has done."
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I speculate his involvement has to do with phony emails, erasing info on the computer and his contact with Casey's friends on behalf of LE. What he said to Annie may have come about after he realized LE knew he had done something wrong.
ETA - Telling Annie not to "protect Caylee" is kind of hypocritical considering he advised his family not to take polys.
And also consider this: What Annie had to say that might incriminate Casey might ALSO have been something that incriminated her (Annie), such as drugs. Maybe Lee really wanted Annie to incriminate herself with the truth.