@kaminomikan He indeed done that, but the guy was an asshole who left him and the other weaker guys to die, at least now that useless fucker is being useful as a shadow.
This other guy (the healer) is another story, and the only fast solution, as explained, was this one, to summon the healer's shadow to save the girl who is almost dead.
I would do as him, think if it's really alright do that to someone who never done anything wrong, at least to me or my/his companions.
No to count that the healer best friend is there watching it all, and in the future, they may have to team up, what would you think of seeing your friend in that state, or what was left of him for that matter.