I don't use that logic. I'm not reasoning that Yamato is > Sanji because she'll join the crew.
Me thinking Yamato is > Sanji has nothing to do with me thinking she'll join the crew.
In fairness, my median estimate of Yamato places her in the same bracket as Rooftop Zoro. If she surpasses my expectations, I would place her above Rooftop Zoro on my tier list.
In particular, if Yamato can push Kaido to use Awakening or gives Hybrid Kaido a high difficulty fight, I would place her above Rooftop Zoro and 1010 Luffy in my tier list.
For an explanation of my logic, see below:
I call things as I see it. And currently, Yamato has the feats and portrayal to be placed above Sanji. Based on how she performs on the Rooftop, I might place her on the same tier as or even above Zoro and Luffy.
The question: "how strong is Yamato?" is IMO an entirely different question from "will Yamato join the crew?". I think it's stupid to try and use your opinion on the latter to answer the former when you can just evaluate Yamato's combat feats and portrayal directly.
If Yamato by herself pushes Kaido to use his Awakening and someone tells me: "X is above Yamato because Yamato will join the crew and Yamato cannot disturb the monster trio" my response would be to block that person. I don't think that's an argument that is sound enough to even bother refuting.
Feats and portrayal take precedence over fandom perceptions of crew dynamics and hierarchy.