This is the bottom line here. A player who takes his jersey off in celebration does so with the full knowledge that he will earn a card for doing so. He's decided that the goal is important enough, his status in the game is safe enough, and his desire to show off is strong enough, that he will eat the card. He's basically saying to the ref, "Go ahead and card me, I got the goal and I don't care!" I would see no reason to let this challenge to my authority go by for free. What if you let it go? -If the same player scores again, you're giving him two shirt removals for the price of one. -If the opposing team scores, and the scorer removes his jersey in celebration, and gets carded, he's going to be confused and frustrated, and rightly so. That team will be angry with you, and the other team (who got away with it) will be laughing at you - major credibility loss on both sides.
You bring up some good issues of game and player management that haven't received enough attention in this thread. MassRef appears to be correct in pointing out that the letter of the law mandates a caution for shirt removal only in the case of a valid goal being scored, but there are other factors that should be considered in addition to the letter of the law.
What would you do if the player a great player scores a great goal and beats the keeper who left his feet to try and stop him, and then looks over at the downed keeper and tells just him but you happen to hear it? "That he doesn't belong on the same field as him".
It was a real incident wish I could remember that players name. The official did not hear it. But the keeper told his coach. For most of the rest of the game he was slide tackled, most were legal but the body sometimes get the player on legal slide tackles. I have seen that happen in the past. Usually the star player slows down and is not as dangerous after that. But not this kid he kept comming maybe a bit of a wisequy that day, but he had a lot of heart.