What does this mean? It means that if one ran across a new yardmaster (trainmaster, etc.) that wouldn't, couldn't or didn't know how to play the game, then you had an opportunity to educate said individual. If you came to realize that the fellow giving you your work wasn't flexible then you merely nodded, took whatever work he deemed it appropriate to lay on you, gathered up your crew and went out the door. And proceeded to work safely.
'Work safely' is a euphemism for throwing out the anchor, which might be described as: working at a greatly reduced speed. After a few hours the yardmaster begins to realize: he has a crew out there, but they don't seem to be getting anything done? And he might then call the trainmaster, and the trainmaster might come on down and walk right with you as you go about your railroad duties. He would see immediately, or if not immediately, sooner or later, that although your feet are moving, the work isn't getting accomplished.
Can he do anything about it? No. Of course not, because you are 'working safely'.
Railroaders are blessed (and always have been) by more and various rules than you might shake a stick at, as the saying goes. This is because railroading is a very dangerous business - heavy machinery, and all that - and folks have always been getting injured and killed doing it, and each time that happened the powers that be added another rule to cover the sad situation that caused injury or loss of life. This has been going on for so long that nowadays that rule book is an inch and a half thick in very small print, and we carry it in our pockets or grips at all times.
A few examples should suffice. The very first rule is, work safely. If you are ever hurt at work you are in immediate violation of rule number one. As mentioned, there is a rule for everything. All a conductor needs to know is the rules, and the rest is easy. Say you tie onto a cut of cars and give the engineer a 'go ahead', the signal to start pulling on them. Wait a second or two, then swing down (stop) the move. If asked what the problem might be, the answer is; the cars seem to be pulling a little hard - time to inspect the track. And inspect the equipment, it could be a car with a sticking brake? Maybe one of the cars has fallen off the rail? Pulling a car that's 'on the ground' or 'in the mud' can ruin miles of perfectly good track, and adjoining tracks and equipment as well. It has happened before, more than once, and that's why there is a rule in the book that says: if the cars are pulling hard, check everything. The engineer knows how to play this game, too. He might advise, 'the air isn't coming up'. Or it might be he that says the cars are pulling hard. Teamwork.
This can go on and on, (in a hundred different forms) and will, for days if necessary, until things change and everyone knows how to play the game.