Uhm -
'concerned' is not the word I'd use in that context (cf. below), but as they say: YMMV (and the subject may be a lacking a few sammiches ...)
He values the ends over the means, but he's not indifferent to the means. If he were, he wouldn't have had the moral event horizon breakdown at the end when he realized he was on the wrong side, because oh well, I guess I was wrong, but whatever, who cares how wrong it was.
Basically the Operative just...er...operates on a utilitarian sense of ethics.
Hmmmh - Way it looked to me is that
basically he likes killing just as much as he likes showing off that he's really good at it and the whole "utilitarian ethics mumbojumbo" is merely his way of not acknowledging to himself that his enjoyment of brutality is what it's all about for him. He's not merely 'not indifferent to the means' - he is actually rather enthusiastic about them, and his whole pseudo-philosophical blurb is designed to obfuscate - primarily to himself - that for him, the means
is the end, really.
We're talking about a dude who
engineers an gravity-assisted 'suicide' and then (apparently sincerely)
congratulates the victim on their honourable death (conveniently forgetting the 'involuntary' element) - instead of simply killing the mark in the fastest, least painful way, which is what a 'concerned utilitarian killer' would have done. He even 'offers' the latter option to the victim (
"would you rather be killed in your sleep, like an ailing pet?"), just before making him a stage-prop in the enactment of his own 'honourable suicide'.
Methinks that his epiphany at the end is not so much about him realizing he was on the wrong side all along as it is about him running out of flimsy excuses for not acknowledging that
he really, really likes what he does, and that
this is his reason for doing it. Recall that Shepherd Book all-but-admitted to Mal that he'd been sort of an 'Operative' once ("The man they like to send is a man who believes
hard") before mending his ways after he realized the callousness of the whole outfit - methinks that 'concerned' is a word more appropriate for the likes of him. Also recall that Mal immediately distrusts the Operative's 'epiphany', whereas he trusted Book implicitly.
Also: