That would avoid incident but the sub might as well run surfaced with active sonar on. The active sonar from the escort would reveal the sub it is escorting to

That would avoid incident but the sub might as well run surfaced with active sonar on. The active sonar from the escort would reveal the sub it is escorting to any passive observers. It would need a directional sonar (not a cheap commercial sonar) and avoiding prop noise that can also reflect off the sub. And if all subs were escorted this way, the navies of adversaries would quickly pick up this habit.