Don’t know who told you that it says “excluding Luffy” in that sentence, because it doesn’t.
That’s the sentence in full.
最初は10人の仲間を1年半で集めようと思っていました。20年以上かかって物語は80%くらいまで来ましたが、仲間はまだ9人です。
Run it through any translation software you like, Luffy’s name (ルフィ) doesn’t appear in it. It just says that the series has ran near twenty years, he originally planned ten Strawhats and there’s still nine.
The page was also posted in 2018, before Jinbei was confirmed to join, so the nine people explicitly doesn’t include him.
Luffy also isn’t Strawhat zero, he’s Strawhat 1. In that page you’ve posted you can see in the picture of the concept crew the numbers, Luffy’s 1, Zoro’s 2, Sanji‘s easy to see as 5, and we can see Brook was originally meant to be 8 and Franky 9.
Jinbei completes Oda’s original plan for a ten person crew. If anyone else comes in, it’s not something Oda planned for back in 1997.
That’s the sentence in full.
最初は10人の仲間を1年半で集めようと思っていました。20年以上かかって物語は80%くらいまで来ましたが、仲間はまだ9人です。
Run it through any translation software you like, Luffy’s name (ルフィ) doesn’t appear in it. It just says that the series has ran near twenty years, he originally planned ten Strawhats and there’s still nine.
The page was also posted in 2018, before Jinbei was confirmed to join, so the nine people explicitly doesn’t include him.
Luffy also isn’t Strawhat zero, he’s Strawhat 1. In that page you’ve posted you can see in the picture of the concept crew the numbers, Luffy’s 1, Zoro’s 2, Sanji‘s easy to see as 5, and we can see Brook was originally meant to be 8 and Franky 9.
Jinbei completes Oda’s original plan for a ten person crew. If anyone else comes in, it’s not something Oda planned for back in 1997.

10 man should do.
luffy does not include himself.