Just because a Buddhist says something doesn't mean it is true

"This type of meditation is not recommended for the meditator who is gay or is bi-sexual. This is by no means stating that the Buddha was against these kinds of sexual activities, but as far as doing Loving-Kindness Meditation, as a primary meditation, it is just not recommended for gays or bisexuals. Buddhism is actually an asexual teaching that goes way beyond anything having to do with the sex of an individual. It has to do with how the Mind of a Human Being actually works. It is best for those who are gay or bi-sexual to do the Mindfulness of Breathing Meditation. Why? Because if a gay person chooses to do the Mettā Meditation and they send mettā to a spiritual friend and that is a person of the same sex, then it may cause some unwholesome states of lust to arise or if the meditator picks a person of the opposite sex, it might cause some unwholesome states of hatred to arise. Either way this is the operational teachings for the meditation on Loving-Kindness and it is not recommended because of the hindrances or problems which may arise and block progress. There is no finger pointing or condemning here. This is just a statement of fact that helps the meditator to progress more quickly in their meditation practice so that they can become even more happy! Not every meditation object is suitable for every personality type." 

Life is Meditation, Meditation is Life! (2014) by Venerable Bhante Vimalaramsi Mahathera.

So my question is what about the dangers to hetrosexuals?

Of course he's from Missouri.