If this guy wanted to do bookclubs, he absolutely could. It's not beyond the wit of man to efficiently pick out a genuine request from the slush pile
If there is more slush and the fraudulent slush increases in quality and scope it must mean that the wit, effort and time required must also increase to deal with the problem.
Dealing with problems that do not give one a return on the investment seems not worth doing, especially when it turns out the most efficient way to deal with this particular problem is to absolutely refuse to do any book club stuff.
Whether there's a thousand spam or a million spam is not at all relevant.
Based on the example emails he posts, the AI bot is NOT scraping his website to individualise the messaging. It isa bulk approach based on ai summaries of the actual books
These scams are a variation of the Nigerian prince scam; they rely on volume mostly