The question here is whether this ebook meets the definition of free as it is commonly known/accepted. As can be proven by the general population calling YouTube free or a mobile game that requires an email free, this ebook can be called free
Yes "nothing is free" yet we still often call these things free. It definitely wasn't free for him to make it.
Average person on here views those hours as billable if they were to do it themselves, when they make decisions about what to do, or alternatives (opportunity cost).
Maybe he should charge them consulting rates for this PDF (and not take their -- correction: an -- email. The horror).
It's only because this is HN that it's even a discussion.
The thing is that calling something free and then asking for something in exchange can trigger someone on autistic spectrum, where likely there is an overrepresentation of on HN.