I took this to mean that bitcoin's issuance rate is more predictable than the rate that physical gold is discovered and mined at. There are unknown unmined gold deposits out there, both on-planet and off-planet. There are no unknown unmined bitcoin deposits.

Also, https://news.ycombinator.com/newsguidelines.html#comments

Generation of new coins is transparent, the total number of coins capped.

That’s predictability. Name one other asset on earth that is easily transferable and more predictable in that sense?

Just because you don't understand the sentence, doesn't mean you have to insult the guy. Other replies have explained it for you.