its not really scrutinizing every detail to expect more of a conversation before offering a position of power to someone who attacked you with lethal intent hours ago and who you know literally nothing about. You can enjoy a manga and still acknowledge its flaws.
"Hey random adventurer that just now was trying to steal from this guy, are you gonna open an adventurers guild in his house" wtf is this writing. If thats the route youre going for it really needs more set up, just feels so forced now.
What you wanted him to accept the execution or destroy/take over the world? This seems like a far more mature choice than either of those lol, to fuck off and enjoy his life instead of serving anyone.