Value systems are a great thing.
As long as one possesses a "justifiable value system," anything they do can be rationalized, even if it's utterly unconscionable.
After all, no one would concern themselves with the unnecessary care of livestock being sent to the slaughterhouse, show excessive emotion for the white mice on the experimentation table, or feel affection for the mined, acid-washed, and machined ores.
That's right, as long as it's not a life considered equal to one's own or even viewed as a life at all, it's permissible on a logical level, as well as from the perspective of mental health and ethics.
Thus, when capturing the "Legion" or any other aberrant creatures, humans would conduct meticulous dissections and analyses; conversely, the "Legion" would do similar things.
No.
The "Legion" would do it even more thoroughly.