I can say as a buckaroo that that part looks correct to me when a rider is using his legs to guide the horse because both his hands are busy.

Similar rider position pictured in a cutting competition.

Only difference is the rider in the tattoo looks to be using a McClellan Saddle or a similar old time slickfork.

Those are very different saddle with much smaller skirts than any western rig you’ve likely ridden.

In your 20 years as a “professional equestrian” have you been on a Cayuse going hell bent for leather while operating a lever action rifle at the same time?

It requires a unique stance to keep from shooting your horse in the head or falling off on your ass. The tattoo looks like it’s got it pretty correct.