This is a description of someone's sexual tastes changing, not their sexual orientation changing. Poem literally cut out the first line I've quoted here.
Now, porn might be one of the things that could inspire someone to explore their sexuality. But I have no reason to believe it can make them gay (or straight for that matter).
How much easier life would be if we could simply program ourselves to be sexually attracted to whatever body type we wanted to like.
Once again it seems to me that those who see porn as a threat, genuinely believe that what is in porn is not just different but better, and we must avoid seeing it or we will no longer want normal relationships.
Candy is sweet, and yet after trying candy, I do not want candy for dinner.