idk man I think the mental gymnastics go the other way around here. You have to make a shit load of assumptions to consume human flesh safely and ethically:

• the person being eaten consents to their body being eaten
• the person has no family or each and every one of their relatives consents and is totally ok with their loved one’s body ending up in a casserole
• the person has no diseases that can be transmitted by consuming some or all parts of their body: prion disease (brain), AIDS, hepatitis and loads other blood-transmitted illnesses, to name a few obvious ones
• there are no drugs or medications in the person’s body that could be absorbed into your system (regurgitated meth, yummy!)
• you have the means to effectively and safely process or cook the body yourself or we set up an entire new industry around mass human body consumption which sounds like the plot of a Stephen King novel tbh

As some have pointed out here, if eating human meat is your only available choice in an extreme life-or-death survival situation, it would have to do, but unless you also have the means to carve up and cook the body, you’re actually going to consume more energy digesting the raw flesh than what you’re getting in return. Humans make for rather poor food overall, that’s a fact. I would back this up with some evidence but I don’t feel like being put on a list for looking up the nutritional contents of human bodies lol