Civil rights CBP SFO

There's no point in filing a formal complaint because nothing is going to get done, I travel fairly often, and I don't want to end up on some "high risk" list, but I haven't stopped thinking about this, so let me share my contempt:

Walked up near CBP agents.
Tried to read sign. Started heading towards the left.
Heavy-set CBP agent glared at me, made a rude noise, and thew up his hands.
"Oh come on!" he exclaimed impatiently, rolling his eyes.
"Oh, is it okay if I..."
Approached heavy-set CBP agent.
He grabbed the paper out of my hand.
"You can go in."
"Huh?"
"You can go in. Shay-shay."
"Wait, do you mean to the lobby or inspection?"
"Shay-shay, you can go in." he stated in an irritated tone of voice while pointing his grubby finger at no obvious destination.
"So... I can leave?"
"Go right. Shay-shay," getting noticeably angrier.
I left.

Unbelievable.
The older I become the less patience I have for impudent behavior. I'm kicking myself in the head for not demanding a name and badge number. This doesn't do much for my faith in humanity.