That the trauma inflicted on them drove them to be hateful, not the trauma inflected from being hateful.

The hate as the result (as in, an unhealthy coping mechanism), not the cause.

but what is the use of knowing that information?

Bottling down the innate sexuality towards the same sex because of societal constraints is bad for the person's well-being. At worst, it self-perpetuate the culture of homophobia because the self-loathing person adds fuel to the fire.

What can anyone do about it.

Learn to accept that homosexuality is perfectly fine, and those with internalised oppression needs therapy.