Maybe he just doesn't want to say the reason. Although I can't imagine it's a legitimate reason.
there was no reason
You really cant say that with any amount of certainty
yes you can
Nope, you really, really cant. Its unlikely - but not impossible - that it could be a scenario where the guy was coerced by an organization like the mob or even a religious cult like stated in #17. Perhaps he was theatened with not only his own life, but also that of everyone he loves, if he didnt carry out the hit attempt. Though sick, thatd be a legitimate reason.
It's unlikely but not impossible that the world is a squrriel's dream. That you are really a teapot with a sentient AI who just make believes that it is a person to drive off insanity. That God exists. That there aren't 17 invisible people around you right now farting silently. That Russia will become the 51st US state
However these are so unlikely that that they negligable to the point that we don't accept them as a possibility.
Thats cute that youre listing scenarios that are infinitely less likely than anything I mentioned. Nice try, I guess. ---