That was from the LA Auto Show in Nov '18. A lot of things can & have changed in 2 years, and I'm sure that was their intent at the time.They said so in their press release:
Rivian’s energy-dense battery module and pack were developed with the most demanding journeys in mind — incorporating tough underbody protection and an advanced cooling system to give occupants the confidence to go further, regardless of terrain or temperature. Adaptive control algorithms learn driver behavior, optimizing user-specific battery management for maximizing battery life, reliability and second-life reusability. Three battery sizes are planned, with the 180 kWh and 135 kWh available at launch and a 105 kWh being made available within six months.
Just to name a few things that might have affected this, you have COVID, Amazon investment & van order, other major manufacturers requesting battery allocations, etc.
I really do understand & would be upset if my heart was set on a 180 (and placed my preorder because of it).
I just think you also have to put yourself in their shoes as well.