I would probably go with auto-reply as soon as he post something, receive the text message and then edit the reply to something meaningful. Fun read! :)
Also, Mark is just one person. Imagine if you opened this script up for use targeting the fans of any celebrity / influencer. Companies would be willing to pay a LOT of money to be able to reach those audiences.
Can't believe I'm advocating comment spam, but sometimes the opportunities jump out at me. :)