Because it would blow his cover!
If he did it would shoot a deadly poison dart into the young lady next to him.
Silent but deadly!
He who smelt it, dealt it.
He who denied it, supplied it.
Ego sum farlo (Latin for I have farted).
Pedere, ergo sum (I fart, therefore I am)
If you fart in a forest and no-one hears it, does it truly smell?