Twilio's stock started dropping [1] with this announcement. Jeff Lawson wants to protect his stock price and restless employees (I am sure there is an internal email forthcoming as well).
The worst (possibly realistic) reading of "Helping to power" is that Twilio confirmed that they are just one of many companies that are powering this solution for Amazon. The implication is that Amazon will keep playing these companies against each other to drive down rates.
It sounds like this was tweeted to quiet the peanut gallery.
Over the last year, I've been exposed to a lot of the nitty gritty of the SMS and carrier world and I was surprised to learn how at scale competition for SMS volume is insane and extremely complex aggregators and the commercial arrangements seemingly incestuous.
The cost savings of easy integration and the appeal of a strong developer ecosystem are less and less attractive as the volume of SMS being managed make the marginal cost savings of going with a direct relationship with Amdocs, Syniverse etc....
