Different states have different tint laws, and I know some tints considered acceptable in Arizona are illegal in California, so if someone were to sell an Arizona car in California, they might later find it doesn't pass a police check.
The dealer "should" be "responsible" and notice this sort of problem, and be experienced with how to avoid it... but also 3 months is a fair amount of time, if it was within a week or two you might have better leverage.
As it is, just do what is cheap and easy, pay the fine, pull out the tint, get an officer to sign off, and if you don't like the dealer now, just don't do business with them again.
Of course, another approach with the dealer is to MAKE SURE YOU GET THEIR NAME of the person who is rude to you, and then SPEAK TO THEIR MANAGER. Of course if it is the Manager being rude, maybe it is a lost cause, but if it is some noob that doesn't realize that the customer is king, you can let it be known. You may also report the business to the better business bureau or something like that, if you speak to management and they still are not receptive.