There's some analysis of this on the ORR site for the Alliance application for Blackpool services, but the upshot was it only just scraped through the qualification.
I imagine this application is a bit of a test of the updated open access rules, and the commercial framework of the new WC franchise.
It also impinges on HS2 planning for the northern WCML.
OA operators are now supposed to pay a share of the underlying costs of the route, rather than just the incremental costs of their services.
We don't know what the commercial terms are for First Trenitalia yet, or what OA assumptions might have been anticipated in the bid.
The WCML already has an "alternate operator" on its whole length apart from Crewe-Warrington-Wigan, though FT is now in the same camp as TPE.
It looks as though Alliance want a full hourly path from Preston to London, shared between Blackpool/Stirling services.
You wouldn't think a 9-car IC225 solution would work north of Preston.
5-car EMUs doubling up south of Preston would be a better fit, or even repurposed 350/2s.