I think what is being conveyed is the actual danger and more importantly stress your tortoise feels in the presence of your dog. Tortoises are a solitary territorial species and prefer to be left alone in a habitat that is their's without intruders. You may be misunderstanding signs of stress as chasing and playing, but that is not the case. Your tortoise is saying leave now I feel threatened and not playing at all. Not to mention it takes a split second for your dog to grab him playfully and cause deadly damage in mere seconds with you standing right there. A better option is creating an enclosed outdoor space for roaming or even a suitable indoor space that is sectioned off from your dog and other animals. This is the only way to prevent your tortoise from chasing and nipping your dog unfortunately. Tortoises also don't like habitat changes and are very fond of the space they call home staying the same hence their territorial nature.
I honestly didn't see anything in @TechnoCheese post that was even close to telling you off or speaking to you like a child? The only thing that was capitalized was to emphasize your tortoise shouldn't be around your dog. There's to many stories about dogs hurting torts that it needs to be pointed out, that's all. We would hate to see you posting something like that. You say you just want advice that's exactly what was being offered. If your doing something wrong people aren't going to sugar coat things just to tell you what you want to hear.
