The way I understand it, WeWork is made for 2 types of people, people looking to rent an office in a prime location, but don't need a big office, or people traveling the world and want a quiet work space with everything needed to hook up a laptop, the former is not offered by the Amex benefit, and the latter is only offered via Amex business platinum benefit.
Here are the points:
1. The space needs to be reserved in advance, meaning when you book your trip aboard you book your office space at a WeWork location at the destination.
2. The Amex benefit excludes the following: Conference room credits and printing credits,
3. You cannot get a private office with this Amex benefit, so I wouldn't call it an alternative to an office.
It sounds to me like a service WeWork only offers to Amex Plat members, not to anyone even for money, their valuation is $2700, maybe it's something they are testing.