This + Twitch Plays Pokemon was what I had in mind when I made this :)
The wikipedia entry appears to be spectacularly short of information on the sheer level of griefing on Twitch plays Pokemon. Just hope that 4chan doesn't find your plant.
Unless his system has vulnerabilities that lead to his personal network or other information, the worst they can do is dry his plant to death, which is obviously an expected outcome. I don't think they are that concerned
It's more likely to get drowned, but I still feel sorry for the poor plant.