When I find plagiarism, I now click "Report to moderator" too. Something like "Plagiarism, please permban. See https://bitcointalk.org/index.php?topic=2855895.msg33874667#msg33874667 for proof." is enough. I don't think all Mods can ban them, so the risk is a Mod just removes the post without ban.
I don't see very much risk in this if you simply create an archive of the post, as seems to usually be the case. Unless moderators/staff are unwilling to perform judgement based upon only an archive, for one reason or another. Even if this were the case, I would think that staff would have access to some kind of "graveyard" "trash" or some extensive "archive" type board. Mostly thinking out loud, but from everything I can gather it would seem that the risk is negligible, unless like usual you have something up your sleeve I haven't considered, in which case..
