It's safe to assume Microsoft felt said manifesto would not help them leverage their many monopolies to secure another one in cloud computing.
If one could be certain of something about the manifesto, its foundations are perhaps "too interoperable" for MS to feel comfortable "collaborating" with anyone else. They have a strong preference to embrace, extend and extinguish whenever possible.
Each and every time Microsoft considered interoperability seriously was in markets they were not sure they would be able to dominate. Interoperability, for them, is usually just a plan-B.
If one could be certain of something about the manifesto, its foundations are perhaps "too interoperable" for MS to feel comfortable "collaborating" with anyone else. They have a strong preference to embrace, extend and extinguish whenever possible.
Each and every time Microsoft considered interoperability seriously was in markets they were not sure they would be able to dominate. Interoperability, for them, is usually just a plan-B.