I'm pretty sure it's by order date. It seems everyone that ordered before March (or maybe it was a certain date in late February) whether Plaid/Plaid+/LR FSD/no-FSD got a Yoke listed on their order. There was no option, but it was explicitly listed in the order form, so most of us felt we were going to get it. I believe Tesla changed the listing to not show it and I doubt that's really going to impact whether they get it or not.
Really, what benefit would explicitly listing that one feature on the order sheet give Tesla? None. It just gives reason for owners to complain/cancel if they don't get it, so they aren't explicitly showing it anymore. They probably should have done that earlier to protect themselves, but they like to push the envelope. I really doubt that one line in your order is going to mean that some models will get it and other won't that don't have it listed. I think they have every intention of putting them in the cars, but they walked it back because they are still working on the approvals and that is a way to protect themselves from the newer order complaints if the yoke is not approved or approval is delayed.
Just my thought, but it seems to make the most sense.... at least to me.