Theologically, assuming (wrongly) Islam to be a religion instead of a War Plan, that Muslim was on solid Islamic theological ground.
The Koran does allow eating the flesh of a dead enemy. Note that Muslim ate his enemies heart raw - just as Islamic (sharia) Law requires.
Muslims ARE cannibals. Islam is cannibalism - along with murder, torture, rape, theft, child rape, small livestock rape, ad nauseam.
I read the Koran and certainly never saw that verse. You got surah and verse?