Thanks for your feedback, I'm just trying to be productive indeed and it saddens me to see there's so little of it here. It shouldn't be hard to at least move a little closer towards each other, but for all the people calling OP ignorant, I see the same ignorance on the other side.
To those that don't see the value; the whole point of my suggestion is to find a way that doesn't impact the NT coach, while opening communication about agency (the issue raised by OP). With this feature, the NT coach would be easily informed of the manager's wishes, and the manager can easily make his wishes clear. It's the first step in addressing the issue.
If anything, it provides data of bad NT coaches who structurally ignore manager's wishes and also data about managers who don't want their players called up. With that data, we can then more accurately assess this issue and check if further adjustments are necessary. Maybe there's almost no manager that has objections, but maybe the problem is bigger than we think.
Also, even if there's 1% when this changes anything, it has more use than the last few pages of this discussion