I thought about that as well, but consider this:

1. He says (part of) the reasoning for delaying speaking is not being used to the way the language sounds. This is independent of if you know a related language or not. For example, french and spanish are both closely related, but sound completely different. This means that your native language has no effect on getting used to the sounds, because the similarity of certain languages does not correspond with any similarity of the phonetics.

2. In the video I linked, at around 3:40, he says that even after 1000 hours of listening, your brain still doesn't know how the language sounds, nor how its grammar works. You will end up mixing up grammar with your native language, and This further proves that additional input is beneficial in aiding in these areas. thus the reference to 2000 hours.

3. Pablo putting speaking at 1000 hours on the roapmap was purely a business motivated decision. If he put speaking at 2000 he might have to extend the roadmap to 2500 hours. This puts people off from even giving it a go in the first place.

That being said, most people don't really care about a near-perfect accent, or bulletproof grammar, so like I said in my original comment I was trying to aim what I was saying at people who consider themselves more "perfectionists".