It's a good idea, but if I made a bot and this idea is implemented, I would program the bot to avoid comment the posts which content the phrase "not comment" or the sub-string "spam". To solve this i think the spammers honeypot should include the "please don't comment" in images with some "noise" to avoid the image character recognition techniques (OCR).
RE: Steemit Comment Spam Honeypot Concept