That description sounds like exactly who Twitter would want to hire. Knowing Scala beforehand isn't a requirement; I certainly didn't. It's possible that by sending the resume only to a specific engineering manager, it got lost in the shuffle. Have you tried following up, and/or contacting recruiting?
We've historically had waaay more engineers than marketers on twitter's growth team. We look at growth less as marketing and more about optimizing (through ux, design, experiment, machine-learning, analytics, etc) all of our possible distribution channels with respect to a set of core metrics.
We lean towards teaching good generalist programmers how to do "growth," which actually doesn't feel much like marketing in day-to-day practice.
If this is something you'd like to do for twitter, and you have javascript, rails, and/or java/scala chops, or you're just a damn good generalist engineer who can pick up anything, send me an email at lzmfAuxjuufs/dpn.