Initial feud

The next week on Raw, Sheamus can face Gargano in a one-on-one match with Gargano seeking to earn the respect of the veteran. In a close match where Gargano can display plenty of his signature grit, ideally kicking out of a brogue kick, Sheamus should ultimately come out on top.
Once again Sheamus should deny Gargano a handshake following the match. Sheamus can proclaim backstage that Gargano doesn't deserve to be on the main roster and that Sheamus has his sights set on clashes with top calibre opponents and not runts like Gargano.
Top WWE star punished? More details HERE
In the following weeks, Gargano ought to face a number of different upper-card talents. He should suffer losses to the likes of Roman Reigns and Braun Strowman but look like a credible opponent in the process. Sheamus can state each time on commentary or in backstage interviews that the result is further proof Gargano does not deserve to be on the main roster.
On the Backlash pre-show, Gargano ought to face Sheamus again, wanting to finally prove himself as worthy of his main roster spot. With Gargano looking like he's going to finally pick up the victory, Sheamus should pick up the win with a handful of tights, leverage pin or some other veteran trick that shows Sheamus felt he had to cheat a little to get the job done.