That plan was tossed aside once Ronan secured the Orb and realized he could get the job done with Thanos’ help.
Both Ronan the Accuser and Korath were introduced in Guardians of the Galaxy, with Ronan serving as the main antagonist and Korath being his main flunky (you may think that honor belonged to Nebula, but remember that she was initially only being loaned out by Thanos).
Until last week, we just assumed that we’d never see those two again, but now that they’re confirmed to appear in Captain Marvel, we’ll get a peek into their past, which by extension will ideally help us understand Ronan better.
In the end, his overconfidence was his downfall, as the Guardians managed to redirect the Orb’s destructive energy back at him, while Korath was killed earlier in the final conflict by Drax the Destroyer.