I admire your intelligent diagnosis
Likewise. Losing the centre hydraulic system is not a “land at nearest suitable” event but you do have to think about the repercussions, e.g. a possible gear down diversion.
In this particular case, if faced with a choice of reduced roll rate and spoiler effectiveness in the cruise or in the landing phase, I think I’d want to have more responsiveness at the end of the flight near the ground, especially if conditions were less than benign. I suppose what Boeing are saying is that if it is an indication issue, then you’ve been one system down during the flight for no physical reason so increasing risk. They can’t write the QRH for all possibilities; indeed it has to work for a below average crew who are having a bad day.
Boeing’s view on “troubleshooting” is that you should exhaust all SOPs first and only if the end result is unacceptable should you start making up your own procedures. I have to say I agree with that philosophy but there are edge cases where the application of sensible airmanship can lead to a better outcome. I can’t find much fault with the logic used above but I can see the point of view of management as they don’t want to encourage off-piste operations too much. It’s a fine line and I expect that privately the operator and/or manufacturer might agree with the actions taken but they can’t be seen endorsing something that could easily be done wrongly.