If the statement above is correct then they can substitute any newer version of the software with the one that was installed when you bought it.
One could argue whatever that because Tesla advertises heavily with OTA upgrades that they are included in the purchase price and therefore should not be able to be unilaterally pulled.
Many software updates are effectively product recalls, even if we don't call them that. Replacing the most recent software with a recalled version could be a safety concern, depending on what bugs exist in the old software.
I don't know exactly what obligations automakers have with respect to recalls, but I would expect that it's something more than just "we aren't allowed to make the car any more broken than it was the day you bought it".
And is the company entitled to reach into your device and remove the software provided and substitute it with an older version?