Have you ever wondered why you always find a jam nut installed on the threaded rod? It is not there to keep the rod from twisting out from the bearing body. As in most installations the attachment points keep this from happening.
For example, in this installation the bearing and the rod cannot rotate as they are locked in place by their fixed attachment points. There is an important principle that must be addressed. The threaded joint of the rod in the rod end bearing cannot handle constant push and pull forces that are applied thousands of times.
Note that with this rod threaded all the way into the body there is still significant play or looseness when I push and pull on the system. The threads are not designed for this constant reversing motion. In fact there is a military standard specification that states this eloquently:
All threaded joints which carry critical loads shall be positively locked in the assembled position so that load reversal at the threads is prevented.
Always use a jam nut to lock the threads in place, this is a must.