I wonder if they got the idea from this forum? A few members here have been using spare CI grates from CharGrillers on top of their gas grill grates for the same results.
For that matter, Steven also has his Tuscan Grill, too:
The thing I like about the new CG grates is that they're quite inexpensive and they're also reversible. The bars on one side are thicker than the other side, so you get a choice of two types of grill marks. I use the thinner side for chicken and other smaller pieces of meat, while the thicker side gives really fat grill marks on steaks of all kinds, like this fine example below:
The pic isn't really to scale - that's a 2" thick rib-eye steak. Those grill marks are about1/2" wide.