"How do you suppose he, or anyone got the idea that "Breasts" are sexual? Our society promoted them to the point that he thinks they are sexual."
That may not be the case. I wrote another messages (up a few) about that, but here's another way of thinking about it...
Some people have phobias about rats, or snakes, or spiders, and so on. If you ask them why, they really can't explain - not in any way that makes sense to anyone who does not have those same fear reactions to those things. They may mention particular features of the object of their fear (for spiders, the bulbous, hairy abdomen, or the discombobulated way in which the legs move, and so on), but that only describes the things which trigger the fear, not the reason for the fear itself.
The reason for these types of phobias is really that the parts of the brain which recognize these particular things also, as a byproduct of how they function, send signals to the fear centre in the brain.
Society has nothing to do with the cause of these phobias - as illustrated by the fact that prople raised in the same society do not all fear snakes or spiders.
If breasts are innately sexual to human males (because of evolution), it would manifest itself the same way - the parts of the brain that recognize various aspects of breasts would, as a side effect, signal those parts of the brain which are involved in sexual thoughts.
It would be equally impossible for someone who does experience breasts as sexual that way (whether it's evolutionary or from experience) to explain why to someone who doesn't share that perception (who would remain in the dark as to why men keep going ga-ga over boobs).
Still, human behaviour is maleable, and can change - not all men react the same way to breasts. The question is whether breasts start sexual and some men get over it, or whether breasts are not sexual, and experience makes them seem that way to most men.
I'd go with the majority on this.