It seems the popular opinion of Kashrus organizations is to require dipping the actual grill. See here by footnote 48 in the name of OU. http://www.kof-k.org/articles/040108090413W-3%20Tevilas%20Keilim.pdf
Are there any opinions that say the metal grill from a barbecue does not need tevila? I ask because I don't ever recall seeing anyone dipping grills; I wonder if they have anything to rely on.
As far as I can tell from the Star-K and the Kof-K you linked to, an overwhelming collection of traditional Jewish sources would obligate the grill in tevilah. Thus I would be very surprised to find such a leniency, and it would be hard to rely on it even if it does exist.
Perhaps (and I speculate) what you have seen / what has confused others about the correct practice is the similar case of an oven rack. The Star-K and the Kof-k pdf you linked to both say that they do not require tevila for initial use. Unlike the grill (or, say, a toaster oven), food is (generally) not directly placed on the oven racks, so they do not require tevilah as they do not fall under the category of utensils used either for directly eating food or preparation of food (and coming into contact with cooked edible food).
