Like with Shinsuke Nakamura not too long ago, Triple H lobbied hard to have Bobby Roode called up to Smackdown instead of Raw. With Vince McMahon continuing to be very hands on with Raw and not as obsessively controlling of Smackdown, Triple H believes he's better able to protect key NXT call-ups on Smackdown.
Triple H in pleading his case to Vince has advocated the idea that Raw is the A-show and guys with main event potential should have to prove themselves on Smackdown first before being moved to the flagship program. This not only benefits Smackdown, which has slowly become more of Triple H's baby, but plays to Vince's tendency to view Raw is the larger priority, no matter how much the company postures that they have two equally important brand.
While not being positioned this way publicly, internally the idea is that talent earmarked for a big push should have to graduated to Smackdown first before graduating to Raw. That obviously was not the case with Finn Balor and Triple H has not been happy with how Balor has been lost in the shuffle at times. Triple H also feels it gives him a chance to prove that certain talent has a ceiling higher than what Vince would assume otherwise based on their height or physique.
It's no coincidence that Raw has been so focused on the very large Roman Reigns, Brock Lesnar and Braun Strowman while Smackdown instead has focused on AJ Styles, Shinsuke Nakamura and Kevin Owens. While the Smackdown champion Jinder Mahal is obviously an exception, it was Vince who wanted a brand's top title on him immediately, but was unwilling to make him the champion of Raw, hence the run on Smackdown.