Slots are not about the present, they are intended for the future. If you thought you could catch that same fish 2-3 months later and he would be 19-21", then would you have second thoughts of releasing him? IF that same 17" brown tugged on your lines a few times, but that same 21" brown would likely ripped you into your backing, why not give it a chance?
BTW. I hope that it is NVR2LATE for the Clinch.
I am a great admirer of spectator sports, especially on television; it keeps the riffraff off the trout streams.