I think it's a religious belief to think splooge has lots of tiny people in it (and therefore one should refrain from pleasing oneself), but it's really just unicellular organisms (which I think may outnumber all the grains of sand on Earth).
He wasn't talking about homunculus, if that's what you mean, but I didn't imagine there could be confusion about what he meant.
It's basically like thinking about the kids that could have had if you had descendants with person A instead of person B. There's nobody around to be disappointed for not being born, but those who got be alive are "lucky" in a certain sense of the word.
