You are indeed remembering incorrectly. Campbell actually spent the entire season in Biloxi. You might be crossing streams with the affiliated demise (for now) of INF Ashton McGee who was injured Game 1 and never recovered. THAT led to the break-out of Cam Devanney.
EDIT to Add: Oh wait, I am now reading your post accurately. Yes, he was last-minute promoted during the first week of the season. He was initially assigned to Wisconsin a few days before the sudden promotion. And, as you astutely point out, continued to perform and never was sent back down. Apologies. I can't remember, off the top of my head, if it had anything to do with an injury - did it have anything to do with a spot opening up when the Crew traded INF Hayden Cantrelle? That was a long time ago in Minor League terms😅