WWE, well, at least Vince, is in the Roman Reigns business. They don't care about Dean Ambrose.
I really don't have anything to back this up but I feel like Roadblock was Triple H's idea. A midcard/NXT showcase with a few established guys to give it credibility. Doesn't seem like a Vince McMahon idea.
Triple H has almost unlimited creative control over himself, I don't think he would have agreed to fight Ambrose at a glorified house show if he wasn't an Ambrose fan.
And wasn't it reported that Triple H was advocating Ambrose win the WWE WHC tournament as a swerve to the obvious Roman victory?
Trips always puts Ambrose over in his WWE.com interviews with Cole, and did a pretty good job making Dean look credible prior to their Roadblock match.
I think it's fair to say HHH likes Dean a lot and really wants to see him be successful. Dean is an NXT guy, he's a Shield guy. I think it's obvious Trips likes him a lot. His booking hasn't been great but it's been a LOT better than previous guys like Wyatt and Ziggler. I think HHH is trying to protect him now for future programs after Roman inevitably fails.
You have to admit - things are set up for Dean pretty damn similar to what the situation Zayn was in after he hit rock bottom in his feud with Neville. If that's what they want to do they have a perfect foundation to build off.