He probably has a bot that refreshes the catalog every few seconds and then fires off the usual spam when it sees a new thread appear. It might be programmed to wait for a post with the word "Dough" or a pastebin URL before it triggers.
>It's unironically not a script imo, it's legit some dude that snipes after the dough.
If' that's the case then it has to be more than one person. It runs 24/7.