The next sentence with the assumption regarding the German history is made by the article author and not part of Scholz quote.
I understand 'we're not allowed' completely in a legal way, otherwise he would probably use different and more ambiguous wording.
It's just a new thing to me and I never read before that Great Britain and France are directly involved with their cruise missile programming. Germany would have to send troops into the war to program Russian targets and 'we're not allowed'. But I'm no lawyer, so I cannot comment what kind of law this would or could break.