I can see why someone would interpret that the rules permit some free climbing. The term "general rule" implies that there are times the rule isn't absolute. If the word "should" were replaced by "shall", the rule would be absolute. I can't imagine that rigging companies would knowingly permit rules violations. They would be subject to a wrongful death lawsuit every time a tower worker dies in a fall.
I wasn't happy when an antenna installation company's worker free climbed my 55' tower when I had my old antenna replaced.
These days if OSHA doesn get 'em the insurance companies will. I know quite a few reputable antenna service companies that will fire employees who free climb.
The ideal system is a safety cable with a carabiner and safety sleeve. I have one of those on my tower. Basically it's a 3/8" length of aircraft cable running up the side of the tower and a sleeve with a brake sliding along. The sleeve attaches to your full body harness via the front D ring. If you are about to fall, brake engages and stops you from falling.
Even the most seasoned tower climbers can have falls and near misses... W2GD had a mishap a couple of years ago where a guyed tower collapsed while it was being erected and John was climbing it but lucky for him he rode the tower down. Broke a lot of bones but he was alive at the end of it.
As such I take lots of safety precautions when climbing. I'm going to be a father of 3 soon and I want to be ALIVE!