You're looking at only a narrow definition of collusion, which is what sekulow is doing.   The illegality of the type of collusion the three stooges were attempting is related to a violation of federal election law, prohibiting foreign nationals from contributing any "thing of value" to an electoral campaign.   Therefore, I believe that, if charges are brought against any of the three stooges, it would involve some kind of conspiracy or fraud.   A violation of the computer fraud and abuse act could also be involved.   But, of course, all this can, and is, being debated by legal experts.   We just have to wait and see how this all plays out.