Unless we somehow developed a philosopher's stone and can operate on an endless budget that is just not true.
The books have to be balanced. End off. Preferrably we need to make a profit every year.
One bad year financially, especially at this point can send the entire project tumbling back down.
The best teams can win things whilst balancing the books.
And just as the books need to be balanced so does the squad. I'm not saying that Toby is actively causing trouble but if he wants out he can be a distraction in the locker room. And having a disruptive voice in the locker room can cause fare more trouble to a title campaign then if we made a profit or loss on transfers.
I agree with your point about obstructive voices in the dressing room. Whether that's a problem with Toby, who can say?
I don't see how this impacts balancing the books in any serious way though. If as a club we are fucked if we don't sell one player for £70M instead of £25M then the club would not be being well run. We didn't buy Toby knowing we'd make a profit on him in the future. What if he had a serious injury or turned out to be shit? I dare say we could make a 100% loss on him and the project would not fail. It's not tied to any one player like that. There are arguments for selling him, in not totally on one side of the debate but I don't find this particular argument very convincing.