Example 1:
A thief anticipates that the fence will buy stolen merchandise, as he did many times before. If not for the expectation that the items could be sold the thief wouldn't steal. Is the fence an accomplice of the theft?
Example 2:
A kiddy porn producer anticipates that his new movie will find audience because the previous ones did. Without that anticipation he wouldn't make it. He shares the movie with a like-minded person who praises it, as expected. Is the viewer an accomplice of the abuse?
Example 3:
A terrorist anticipates that the murders he is perpetrating will find approval within a certain audience, and that approval would further his goals. The expectation is justified because of the prior approvals. Without the anticipated approval he wouldn't commit the murders. The audience cheers, as expected, and that does indeed further the terrorist's goals. Are the members of the audience accomplices of the murders?
Please don't treat these examples as three separate questions; they are just illustrations. The question is a generalization of all of that: "Can approval of a crime after it has occurred make one an accomplice?"