I agree, a wire-protocol is vital for interoperability and much more valuable in my opinion than an API. To present MAMA as an alternative to AMQP, as the article does, is not accurate. MAMA is an alternative to JMS or WCF. AMQP does not define an API, MAMA does not define a wire-protocol.
Standard APIs are all well and good in - addition to standard protocols, not instead of them. Whether or not MAMA succeeds in that area remains to be seen.