User blog comment:Hawki/Scavenging for a Feeling/@comment-4817-20180728013530/@comment-250398-20180728070207

It’s very strongly implied Stukov left the Swarm. While Heroes of the Storm isn’t canon, all interactions they made for him say he left the Swarm and made the infested their own faction. While it’s not canon the fact they work with SC writers implies that’s the direction they wabted to take him, especially with his absence (as a senitient infested human would likely have been useful in negotiations with terrans)

And it’s not that they’re making SCIII. It’s settling the seeds of the story. When they put out Dark Origin they didn’t plan out SCII’s development, I expect this is much the same situation. Laying the groundwork should they decide to return to the universe.