My understanding is Tesla historically doesn't give you any trade in value for FSD so his estimate shouldn't be impacted by whether or not he's transferring the software license. Has that changed?
I am not in the market, but there would not have been any way to determine that in any real sense before tesla offered this one time transfer option. Either your car had FSD or it didnt, and they gave you a price.
I have seen several posts here where people get an offer, or a lower one if they are transferring FSD. They certainly are not giving retail value for it, but if you are transferring it, the offers are lower, so by definition it has whatever value between those two numbers.
Or, TL ; DR , there was no real way to determine that before, but now there is.
For this specific OP, as I said in my other post, they also didnt talk about time frame between the two offers.