Why the Axis didn't used POWs as "hostages" to protect their naval convoys?

I am sorry if the question sound cold and heartless, but such was this senseless war.
In the weekly episode number 162 it was mentioned the dire situation of Axis convoys in the Mediterranean, how many Italian merchant ships were sunk or captured by the Allies and how the merchant fleet was drastically reduced compared to last year.
Did the Axis ever tried or at least thought about putting Allied POWs on their ships, in the hope the Allies might had thought twice before sinking them? I’m sure the high-ranking Allied officers might not had any sort of scruple on sinking them, regardless of the presence of fellow contrymen, but surely the soldiers and officers directly involved in the actual sinking of said ships might have been more reluctant.
Thank you for the hard work to all of the WW2 and Time Ghost staff.

That would be a violation of Hague Conventions which Germany and Italy signed before. Then Allies could use captured Axis POWs as human shield in battle (which they captured a lot in Africa) or “hostages” to protect their own cargo ships against U-Boats. Nazis might not give a damn but Italians could.