I'm not sure what the regs are on the South Platte, but if someone wants to take a picture of a nice, legally caught fish and share it with me, the only reasonable response I can think of to that is: Thank you.
Every one of us killed a few fish this year, intentionally or unintentionally; that is the inevitable consequence of catching fish. Most of us tried our best not to kill most or any of them, and so I've got no beef when one of us goes ahead and kills one or two (as long as it was legal, and/or the fish wasn't from a threatened population), either because he wanted to eat it, or because he wanted to show it off. (If you really believe vanity has no place in fishing; well, I have absolutely no idea what to say to that.)
I've got a lot more patience with a chap taking a picture or two a year in an "improper" pose, than guys who "inform" us (not bragging, no, never) about the 20 or 30 or 50 trout they "properly" released (killing 2 or 3 or 5; I don't care how good they looked when they swam away). Or guys who think it's OK to fish anywhere for anything anytime because they always practice "proper" c&r.
When we catch fish, some of them die; deal with that and be responsible about it. If we're worried about it, some of us might do better considering a little more carefully how many and what kind of fish we hook and where we do it, rather than picking on somebody for MAYBE killing one rainbow (from a drainage where they're not even native).
Again, thanks for the picure. And stick around, most of us really like it here on this board; I'm sure you will too.