Well, if the people of Minn and their visitors have any balls, they'll boycott those cabs. Actually, I would find such a sign helpful whether I had a bottle of hootch with me or not - I would know which cabs not to patronize.
I despise Mulsim cab drivers. I refuse to ride in their filthy cabs. Why help them earn a living?
I think that the problem is that you can't refuse them off the bat - you have to wait on the line until the cab comes up, and then say you're carrying alcohol - and do the same with all of them until you get a non-Muzzie cab. Since about 2/3 of the cabbies in MPS are Somalis, chances are you'll be there a long time.
This is just a demonstration of power. It has nothing to do with alcohol; nobody is asking them to drink it, sell it, serve it or even know about it. It's just another way of pushing Americans around.
Good Idea - free sticky lapel labels of beer cans about 6" tall so all can see - That will put a crimp in their take home pay!