I would imagine they would consider tint an "obstruction". You are correct though, it is up to the cop.

I have heard stories of troopers pulling people over on the turnpike and making them either take the tint off there, or having their cars towed. It all depends on who wants to read the law to the letter.

Luckily they took window tint out of the inspection process. Its not fun being on the receiving end of a trooper coming to see you because of an inspection issue.