M0nica
Well, the transactivists have a very limited knowledge of anatomy if they do not realise that men have breasts and nipples!
Since everyone, all sexes, all genders, all ages from birth onwards have both breasts and nipples those words those organs those those parts of the body and the names for them cannot be gender, sex or age specific.
In 19th century literature, a man's chest is not infrequently referred to as a breast. Especially when talking about emotions which men appeared to feel in that anatomical area.
Of course, language evolves and we now talk about 'manly-chests' but, women have also been described in the media as going "bare chested" - on a beach.
So the words can be applied to both male and female. However, feeding babies has always been breast-feeding and as you say, men have them and if they are feeding a baby, they are breast-feeding (the mechanics of which is another topic) so replacing that with chest-feeding is entirely unnecessary, just another attempt at diminishing women.
Have you heard about the alternative names for a vagina? 
Though it's no laughing matter.


