Absolutely ridiculous thing to say. It has nothing to do with gender. It simply means 'it is so' or 'so be it'. It's not even an english word, it's a hebrew word that has no connection to the words man or men. The words for man or men in hebrew don't even have the same phonetic sound!
And if we really want to dig deeper into it and ignore that it's gobbledygook for a second, if 'man' is the opposite of 'woman', and amen is to say "it is so", then the only thing awoman could mean is "it is not so", which makes the whole thing sounds even more stupid.
What Cleaver did was basically sacrilege...which also happens to be a well established sin, often called a sin of irreverence.
Was told once that woman was shorthand for wombed man.
Man as a word favors the feminine. In the east and in Egypt there is the word RaMa. Ra is the masculine principle and Ma is the feminine principle.
So if our race name was really biased towards the masculine, we would be calling it Ran instead of Man.
You should watch Donald Trump Jr's speech from tonight.