First off, Elon did not say all owners who don't have it currently can buy it for 2k. The discounted price only applies to those who purchased prior to the price drop when 35k model was put up.
Now with that said I don't know why it would be showing for some but not others. I know there's been reports of some people seeing Free lifetime supercharging randomly showing up in their account, then randomly dissapearing- among other things. My guess is that there may be some database glitches of sorts that is causing wonkiness and inconsistency among accounts. As far as we know, all eligible owners should see the new price show up in a few days as their system updates.