Yeah, but can he stop it!!!

I was thinking the same thing.
I'll ask because I simply don't know, are there trailer brakes available for something like this?
I pull a large gooseneck trailer with my Diesel Pick Up. Getting it moving is never an issue but there are times when a controlled panic stop is a challenge. Especially when fully loaded. I can only imagine a panic stop with that rig. Hopefully, there are brakes on that tow behind.
Having never pulled a trailer on a bike, I also have a question about braking while on a curve or in a turn. Seems like that additional drag would add some handling issues on a bike. Just curious.