What would be the real-world implications of the Kessler Syndrome? is essentially an engineering (applied physics) question. If we ignore the specifics of that question, should we accept applied physics questions here?
To suggest another example in the same category: "Can you use any semiconductor material to create a LED?" - undoubtedly solid state physics, but not really academical.
Yes, of course, applied physics questions are allowed. But the questions should be specific enough to actually be about physics. The second example, about semiconductors and LEDs, certainly seems fine (although it could be interpreted as an electrical engineering question or as a solid state physics question), but the first one about the Kessler syndrome encompasses a whole range of topics: aerospace engineering, materials engineering, environmental science, and probably some fields that don't even really have names, in addition to just physics.
Also note that engineering is not exactly synonymous with applied physics. At least, I think not.
