In this case, it's probably more like how a doctor "delays" administering treatment to a terminally ill patient while doing triage and gives morphine instead to ease the pain.
When plans for a Tizen phone were first announced, we were skeptical of the chances for success and of docomo's motives for release. At the time, the only consideration was Android and how it greatly hindered the carrier's abilities to charge money for things like putting a song on your phone or a new ringtone. Now that docomo has the iPhone, I really don't see Tizen in the picture. Making their services compatible also would have required a lot of resources, leaving little left for Tizen.
As data-based, alternate communication forms (Skype, Line, VoIP, hangouts) continue to eat into profits from voice calls, docomo is still looking for a way to increase revenue from premium content and related services because they are shifting 10% of their workforce, or roughly 2000 people to content and e-commerce.
For now, Tizen is not going to be their solution, which is probably a good thing.