But everyone is quick to chastise the desperate player for playing within the rules
But provided things happened like the one guy said... (which is always a fairly large caveat) the first player wasn't actually playing by the rules.
The other guy had three ships to fire, when he fired with this second ship the guy telling the story said 'I'm going to shoot with Dengar' at that point the other guy effectively ignores him and shoots with his 3rd ship bypassing the chance to use Dengar, and then the TO decides that it's a missed opportunity.
But in this case it's not, it's that one guy skipped the other guys chance to perform an action. Now were it me, I'd insist that I take the shot with Dengar, but apparently up to that point both sides had been playing fairly casual... Until this point where the one guy threw the whole concept of flly casual out the window.
At that point I think any reasonable person would start to respond in kind, or at least really think about it.
Even if we call what happened a missed opportunity, if you deny someone a take back no matter how big or small the impact, then you better not expect to get any yourself from that point on.
