a) It is one thing to require something, another to prohibit it. Anybody can take a hat off.
b) What man is going to leave a hat on under circumstances when even a priest may not wear one?
c) The passage in question speaks about men and women in different terms, and in terms that imply that this is a custom that is under the jurisdiction of the bishops.
“Any man who prays or prophesies with his head covered brings shame upon his head. But any woman who prays or prophesies with her head unveiled brings shame upon her head, for it is one and the same thing as if she had had her head shaved. For if a woman does not have her head veiled, she may as well have her hair cut off. But if it is shameful for a woman to have her hair cut off or her head shaved, then she should wear a veil. A man, on the other hand, should not cover his head, because he is the image and glory of God, but woman is the glory of man…But if anyone is inclined to be argumentative, we do not have such a custom, nor do the churches of God.”
So in other words, a man keeps his head uncovered because he is the image of God. A woman, though, covers her head because her hair gives glory to mankind. The Apostle writes, “if it is shameful for a woman to have her hair cut off or her head shaved, then she should wear a veil”. The implication is that if a cropped head is not a shame for a woman, then the veil would not be necessary. The Apostle also implies that the custom depends on the usage of the churches of God; that is, the custom is what the bishops decide the custom is in their own churches.
It would seem that the bishops have decided that this is what the passage means, at any rate. Their conclusion about the custom in their own churches is all that I need to know. Luckily, those women who believe their heads should be covered are not forbidden to do so.