We can disagree, I guess.

I will go on what I was instructed in my LSA Repairman class. After a long discussion on this very subject, the instructor (an A&P with AI) made perfect sense to my engineering perspective. A mechanically locked nut and bolt, by definition, must be loosened to align the cotter pin. This will allow the hardened ball of the rod end bearing to rotate on the soft bolt shaft, which will cause wear.

Using a nyloc bolt allows the hardware to be tight on the flat sides of the ball in the bearing, making this hardened ball rotate in the socket it was designed to move in. There is no movement of the hardware in relation to the ball or the actuating fork in the joint. So there is no concern of loosening the nut on the bolt or grinding wear thinning the shaft of the bolt.