From my understanding he didn't feel the need to kill it until it started wrapping him up. This is when his friends jumped in with a knife. Seeing as they are an invasive species, maybe he was just trying to catch it not realizing how big it was. I highly doubt an owner who put the time into caring for a snake that got that large would want to depose of it in this manner just to become a hero.

I wasn't there so all of this is conjecture. Needless to say, that is one large specimen.