Lol, I actually missed the box (in ch 66) that said the ninja was hired 4 months prior.
I was actually wondering why the old man still wanted to observe MC.
So, the joke caught me off guard.
There is. It's in the title: Messiah. Savior. Possessing that title and living up to it cost him everything he had and then some more. I doubt he'd be interested in repeating the disgraceful experience. S rank, to be one among many, ought to be just fine for him.
ahh sorry, last chapter I tried to use gender neutral with the ninja, this chapter felt more like it was a he, so let slip the guy...
and my point was more like the ninja was doing the silly bad camouflage thing like ninja murasaki did in dragon ball.