From a philosophical POV, it shouldn't matter if the other coordinator is involved in illegal things, especially if the default is that the others with whom you coinjoin with are preset. Even if not preset - what, are we supposed to ask the entire personal history of the others involved? That defeats the point. Even if you asked, your chances of getting a straight answer are near 0%. I think it's an issue of "guilty by association," which fortunately does not fly much anymore in today's time.