1) I know of no code provision that pertains directly to the development of U-bars.
2) I think that most engineers, in many situations, would consider U-bars to be a better development situation than a pair of independent hooks. I know that I would.
3) For flexural applications, it's unlikely that you'd ever have both sides of the U-bar in tension concurrently. As such, you may not really be "sharing" the hooks in any way that matters.
4) As others have mentioned, the detail presents constructibility challenges.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.