The point about temporal coupling is not solved by asynchronous messaging either. If the client requires a response before proceeding then client will block regardless of type of messaging used and the responding service will have to be available for the client to receive a response.
I think that part of the problem with REST implied by the article is that it is purely request/response, rather than supporting full bidirectional communication.
To me the term "temporal coupling" is skipping some details, since the real consideration is the duration of the transaction vs the duration of the transport session. REST-over-HTTP can't directly represent transactions which span TCP sessions, and this is a problem if the transaction is very long or the connection is choppy.
