The Route Banbury issue is more a XC vs Virgin thing, while the Route High Wycombe issue, I agree is more Chiltern vs Virgin.I understand what you are saying but it seems a bit harsh on Virgin if somebody has a route Banbury ticket and gets a zero excess to travel from Euston if the ticket money is allocated to Chiltern.
But I always assumed revenue was re-allocated based on these excesses, do you have information to the contrary? If you can reveal it I would be interested (feel free to PM me if you can't make it public).
That said, revenue allocation is irrelevant when it comes to validity and is of no concern to the customer.