You could decided that you didn't play that one hour on Holodeck but o Triblle. It's just like for example Korzeniowski or any other Olympic Champion could said: "Guys I missed the last Olympic Games, but I want the gold medal. Can you sell me one?"
While I can understand your frustration, you could also get that tribble by being idle at space dock for an hour or two.
It would have been cool if they added them to the breeding list along side the purchase option but meh, what is done is done.