I was in a burger shop and on the cash register was a sign with all the credit card logos on it. At first glance, I assumed it was a sign signifying "we accept these cards". After they told my wife "cash only" did I realize there was a red circle around the logos with a line through it.
But the mind doesn't work that way.
Show me credit card logos and I'll think you accept them. Don't draw attention to what you're against. Show me a sign that says "cash only". Draw attention to what you're for.
If you're going to use what you're against to draw attention to what you're for, don't be surprised if people think the opposite.