Does our liberty in Christ have limitations ? Yes. Claiming the following means we can now lawfully eat anything (glass perhaps?)
KJV 1 Corinthians 6
12 All things are lawful unto me, but all things are not expedient: all things are lawful for me, but I will not be brought under the power of any....
KJV 1 Corinthians 10
23 All things are lawful for me, but all things are not expedient: all things are lawful for me, but all things edify not.
Makes a mockery of God's design. He has stipulated what is food. Anything that Has said was not to be eaten, is therefore not only unhealthy... It isn't food. Glass can be eaten, but it isn't food. Pork can be eaten. But it isn't food. It's taste... Its ease of accessibility... It's cheapness... Does not make it food. There is no such thing, and there never has been any such thing as unclean food. I challenge anyone to find a scripture reference to unclean food as if a certain item was food but God arbitrarily forbade it from being consumed. No. Good forbade certain unclean animals from being eaten because they weren't food. And why are they not food? Because they are poison. They kill. Maybe slowly, but they kill.
So cannibals can most assuredly be asked to give up their practice on the basis that human beings are not food. Just like swine, oysters, lobsters, mussels, paua,kina, toheroa, and kereru. (Some NZ so called delicacies included there all of which I have in the past eaten and enjoyed... But enlightened now I refuse because as God said, these things shall not be food for you.) Science today totally vindicates God's choices as to what constitutes as a recommended diet as per the Manufacturers instructions.
And yes, it is total hypocricy for a Christian to demand of a native pagan that he should refrain from cannibalism while the Christian later instructs him that all things are lawful.