Fame at last
You say that, but... I mentioned elsewhere that the Penistone Line almost closed between Huddersfield and Penistone because WYCC didn't want to pay for it. The line was mostly singled and the Clayton West branch closed to save costs. Then the Independent Republic of South Yorkshire didn't want the route redirected via Barnsley, they wanted the direct route via Stocksbridge and Deepcar retained.
If a TPE service was diverted, which stations/stakeholders would miss out and how much would it cost TPE in lost revenue or additional mileage? And would Wakefield Council make up the difference? That's why I don't think TPE would run a service permanently via Castleford. Sadly there's no rail link between Monkhill and Baghill, so you
couldn't run Sheffield-York via Castleford either.