I was thinking the same thing then put some numbers in to a right triangle calculator.
For demonstration purposes I used this site: https://www.omnicalculator.com/math/right-triangle-side-angle
Say the trans is 1" above the rear yoke, a=1
distance from output shaft to rear yoke, b=55
Angle a = 1.0416 degrees (this is using his straight shaft method)
Now, with trans yoke pullback:
Trans is 1" above the rear yoke, a=1
distance from trans yoke pivot to rear yoke, b=52 (SWAG! yoke + pull back is 3")
Angle a = 1.1017 degrees
So using his method vs using a yoke gives him .07 degree error. That's pretty tolerable considering you'll get that much error from the measuring tools themselves.. Not bad?