Hmm, Are you sure you denied him off your plot? If you did, It's probably either a glitch or he's probably using some type of hacks. Therefore if he is using hacks that are legal on the server it isn't punishable. Unless he's using hacks to effect the server to either crash, lag or anything other than that. If you don't want him on your plot. Try to make an support ticket, Or contact a staff member to force him off the plot.
If this is a glitch, and you're not trying to troll us, report it to @Jess or email [email protected]
Well it said in chat that he was already denied but still got onto the plot. EDIT: If you think i'm lying go try it yourself.