Of course, the author would be too much of a pussy to make MC finish the job. It's getting really annoying seeing MCs in mangas forgive, let go or lose the opportunity to finish off the villains, for either somebody else to kill them, or for them to come back in the later chapters.
Tons of people saying blabla karma satisfying and so on... They did a miracle survival arsepull only to reverse it a chapter later! This entire chapter was completely pointless!
He took the dudes legs; in any other situation he'd have bled to death.
I think I can forgive the MC for hesitating for a split second when he thought the dude had no escape. Miscalculating is far more understandable than our normal "oh well if I let you live you might reform" bullshit.