The greatest gift you can give your mustang is patience.
Remember, he’s been chased by helicopters, probably for several days, jammed into a chute and freeze-marked, had his boys cut off, brusquely handled by wranglers, and hauled off to an alien world.
Now you want to put him in a confined space and try to make friends when he doesn’t trust you and is ill-prepared for the experience?
How do you give him release when your presence is pressure?
What kind of learning happens in this environment?
The first thing you have to do is sack him out to you.
Let him come to terms with his new surroundings on his own timeframe. Spend some time with him doing chores (scooping poop and filling water buckets). Give him a chance to figure out you’re not a threat. The older he is the longer this will take.
An exception might be when he is aggressive and dangerous (because he was taught bad lessons by someone else) and will be put down or sold at auction.
It’s not the rope.
He’s not flighty.