Why "angels" doesn't mean "demons"

 There's a teaching that pops up from time to time in the head coverings community, that goes something like:

we wear a head cover as spiritual protection from demons

or

a head cover signals to demons that they can't touch us because we're Christians.

Let's look at the first one:

let's stick to what the Bible actually says. If 1 Corinthians 11 says that wearing a head cover prevents women from dishonoring their heads, if a head cover signifies creation order, and "because of the angels" - let's go with that.

Nothing about spiritual protection there.

And the second:

"demons can't touch us..." 

Ask the Apostle Paul about that one.

So to keep me from becoming conceited because of the surpassing greatness of the revelations, a thorn was given me in the flesh, a messenger of Satan to harass me, to keep me from becoming conceited. (2 Corinthians 12:7)

I think that we can safely believe that Paul prayed and prophesied with his head uncovered, as he was the one who gave us the instruction...

1. Man prays and prophesies with head uncovered

2. Gets a thorn in the flesh

3. The thorn was a messenger of Satan.

Following the head covering/uncovering instruction didn't stop Paul from being harassed by Satan.