The scene was, in my opinion, inconsistent with the rest of the movie.
It's not a matter of suspended disbelief, it's a matter of being consistent to the premise that the story is based on.
The movie had followed, more or less, our standard reality. (Bullets break glass, Tom Hanks character was careful and good because he didn't want to die, other hitman was remorseless and good at self-preservation) Then at the end, it all goes out the window so (...they can wrap things up quickly? ...they can change the movie into a little morality play? ...I don't really know why.)
It would be sort of like at the end of a relatively normal Superman movie, Superman commits suicide by jumping off a building then at the funeral, Lois Lane says she never liked him anyway and they find out he was a child molester on the side.