to avoid being an A$$hole is to avoid actions that cause others to consider you an A$$hole. A good way to start is to ask yourself if the things you say or type will be considered offensive by those who read them before expressing them.
Yes, there are populations of Dollys that are considered endangered, as there are of Steelhead, Salmon and just about every other gamefish we might consider targeting on a fly in the pacific northwest. There are also populations of each that are considered healthy enough to support C&R (and even harvest) fisheries.
An example are the Dollys on the Upper Skagit. Even though they don't currently allow a harvest on them (a recent and enlightened move by our DFW), the #s of large Dollys is really impressive and indicate a very healthy population. No, this is not my speculation. It came from Curt Kraemer, at the time the Resident Biologist for the WDFW and also leader of an ongoing study of Dolly Varden trout in this watershed.
Yes, you can argue that if you can't harvest them then you shouldn't fish for them. That would effectively eliminate many of the C&R fisheries for wild steelhead on the Skagit, Sauk, and other rivers still open.
Or you can A$$ume that he was targeting them illegally. But, with no evidence to the contrary, I usually give anglers the benefit of the doubt.