Hendy's approach seems to entirely ignore the fact GBR will obviously be a vertically integrated national entity for the purposes of funding and accountability. Or that things wouldn't have been quite so easy at TfL Rail if Thames Valley Rail or Kent & Sussex Rail had equal statutory rights to make demands and expect answers from GBR's regional manager on their patch.
Here's a radical solution. Don't have GBR at all. At least not as a national entity. Transfer full ownership of the railway in each of these local fiefdoms to their Governor. They can make the case to the DfT directly for funding, on a theoretically equal basis.
Any and all matters requiring cross boundary cooperation or a national approach, can be sorted out through cooperative entities funded and managed by the fiefdoms. Some of who naturally would want to use the brand GBR, notably ticketing and intercity services.
That would leave legislation and a truly independent regulator solely to ensure basic safety and secure the rights of open access and freight operators to use this public railway, and achieve other relevant national objectives, such as net zero and levelling up.
I can't see many downsides. It wouldn't be in any Governor's interest to screw over a neighbour or the collective, since they would be directly and indirectly harming their own interests. Just as it should be.
If it directly hit Andy Burnham in the pocket or his fellow Railway Governors chewed him out every time he sidelined a London bound train or GBR TransPennine service to benefit his Bee Trains, he might think twice and take truly holistic approach to such decisions. Show he is actually an "informed client". Which tbf, he does come across as. Which doesn't necessarily mean he is.
The only way Hendy's approach will work is if all local clients are forced to make their requests/demands to the GBR CEO level, as statutory equals, in recognition of the very obvious fact that it really doesn't matter what "willing railway people" at lower levels say if it conflicts with the GBR national strategy or the Treasury set budget.