Is not bullshit at all but it is classed as a dodgey way to boost your weeds strength and yield.
The female contraceptive pill is basically chalk and estrogen and a bit of colouring.
Estrosoak is used widely in Amsterdam to feminize seeds and boost buds and the chances are that if you have been buying any commercial street deals anywhere in the world,that the buds you've smoked have been boosted with estrogen.
A sure fire way to tell is if the unfertilized seed pods look unusually large.
As far as i know they are trying to create a link between the fact that smoking bud thats been constantly flushed with estrogen can lead to man boobs.
Soaking seeds in estrosoak or female contraceptive pills does not lead to man boobs or leave any thing bad in the end plant but pouring it into the soil or growing medium does leave high amounts of estrogen in the plant and is especially bad for male medical users that consume their weed and because it is a hormone it is hard to flush out.
There is as far as i can tell nothing wrong with using this product on your seed but i would not recommend feeding it to your plants as its virtually unflushable