In my opinion those who believe in God should well know that God is the only one having the right to take someone's life (and only God, not humans who claim to speak on his behalf) and those who do not believe in any God should well know that this right isn't owned by anyone.
So I do not think the point is that 3 people have eaten the boy, the point is that they killed him.
So, for me, the question is quite simple: no one should think to be allowed to kill anyone.
[clarification for Sarras: what's writed up here
is my answer to the question 'Was this right?'... I think that was wrong and this has nothing to do with religion or religion in courts... by the way I think right places for religion are churches or temples... not courts]So, of course, in this case I don't think the degree of necessity exonerate the 3 sailors from guilt (that could have been different if the boy was tryin' to kill them and they had killed him trying to save their life... but that's not what happened).
[clarification for Sarras: THIS
is my answer about the trial]Furthermore, from what I remember, it is quite dangerous to start thinking that the weak, or sick, or the 'different' is less important than the healthy or the 'normal'.
So the additional details do not change what I have said so far.