I can't say that I have ever checked for leakage there. I guess it could happen. None of my bikes have anything other than the bolt and a lock washer. They all have split lock washers, but MAY have had a different style lock washer when new.
The bolt is a specific length. Too short and you risk stripping the hole. Too long and you cut off the oil supply to the rocker. And yes, if the threads are buggered, you can just rotate the shaft. Just make sure all the debris are out of the hole.
Hope this helps,
Tom