You'd also have to have him also turned into a pariah of the highest caliber and sever his friendship with John Stewart. Remember; John Oliver was a 100% failure and basically was so reviled as an unfunny stand-up comic, that he was BLACKBALLED from all the various panel shows in the UK due to him being THAT fucking unfunny and a ratings killer.
Once he successfully wormed his way into John Stewart's heart and inner circle (due to Stewart wanting another nerd type to replace the departing Mo Rocca and getting dazzled by Oliver's british accent and incel looks), Oliver's past as far as all of his unfunny TV appearances and media coverage of him being super-unfunny/hated was memory-holed due to Oliver gaining gatekeeper status via Comedy Central and Stewart; meaning the UK comedy scene that rightfully told him to get the fuck off the island were suddenly throwing themselves at Oliver in hopes of breaking big in the US now that Oliver was in a position to get revenge on those who shunned and blackballed him.