The short answer is "yes, insurance companies can deny your claim if your tint is illegal".

Most insurance policies or Product Disclosure Statements will include a condition that your coverage is void if your car is not roadworthy or does not otherwise comply with the applicable laws and regulations.

Having an illegal tint is certainly a legitimate ground to deny a claim, particularly if there's any chance that the illegal tint contributed to the accident that is the subject of the claim.

IMO, it's not worth it to run with the cool crowd. Just get some dark sunnies