Hobin is going to successfully execute the arm-grab technique, but he wont be strong enough to hold himself up/he gets his balls grabbed or something, and he'll slide down the arm. That'd be a classic HTF kind of situation.
@Tibanderstap There are multiple variations of an arm bar i.e. https://cdn.evolve-mma.com/wp-content/uploads/2018/01/song-ka-yeon-armbar.png. Some more effective than others just due to position. But the principles are still the same: tie up the arm while being cognizant of the elbow-to-hip placement and wrist control. This is a "street fight" and to a person inexperienced in jiu jitsu/grappling, the setup angle can be relatively negligible. The author has a few plot holes through out the story, but this one isn't too bad.