I dunno how else to explain it. Taking a pic when you bought the card doesn't = proof that you sent it in undamaged. Them showing you a pic of the cap missing isn't proof that some jerk on their end sabotaged your card.
The cap is missing, who knows how that happened. It's like chess, it's going to fall to UPS cuz after they deny causing the damage... what are you going to do? Do you expect them to say oh yea, Johnny XFX you've been a bad boy? C'mon?