Their RDS and ES are 500k. They still need to pay for EC2, S3 and any other services they might be using, like ELB and Elasticache. So probably higher than that.
He also did not mention if they are going to self-host, colocate, or rent bare metal in a more traditional host (like softlayer). Probably colocate as I think that’s how they used to run?
Both your points are still valid though.