That would make sense except I bought before the $2k raise and I also can upgrade for $7k. I think the decrease is simply an acknowledgement that most people won't pay $9k, which was always pretty outrageous given those of us with 60's passed on paying $6500 at delivery, so why would we consider $9k? $7000 might tempt a few of us who might be second guessing our original decision but $9k is too much of a "penalty."
Actually, it may be much simpler than that:
1, At the end of November last year, the base S60 price went up by $2K. S75 price stayed the same.
2. Pre-delivery price difference between S60 and S75 went down from $8500 to $6500
3. The post delivery upgrade price for most features has historically always been pre-delivery price +$500 (EAP and FSD are the exception - it seems Tesla wanted to add stronger motivation to pre-buy future functionality).
4. Tesla's policy historically has been to always charge current post delivery upgrade price, no matter what the price was when you bought the car. Some people who purchased their cars without the AP1 enabled and wanted to enable it later, were upset because the AP1 price went up at one point. They had to pay the current price, so it would be consistent that if an upgrade price went down instead, same would apply.
So, assuming this is not a temporary anomaly due to inability to track who paid the higher or lower base price, this makes total sense and is consistent with Tesla policy. Now, had they made the $2K increase by unlocking a little more range and calling the car S65, then they could have a 65->75 upgrade and 60->75 upgrade as separate items priced separately. I was actually thinking that is what they were going to do when they pre-announced the base model price increase, but it turned out to be just a straight out price increase for the same product.