If you do not have the Freq Pin, it is in someone else's possesion, they are flying, you turn your radio on, cause them to crash. Then you should be held responsible. Atleast that is the guidelines my club uses, and all the members agree with it. From day one at our club, you are told to always get your Freq Tag, before turning on any equipment. I always make it habit to do so before even unloading my gear, even If I am the only one at the field. So I say yes, you should be held responsible if you turn your Radio on without Freq Tag in your possession and cause another plane using that Freq to crash. Might sound stupid, but try to look at your TX as a loaded gun when at the field, and the Freq Tag is the Safety. If you pull thr trigger with the Safety on, everyone should be safe. With safety off, you just may shoot someone.