I have printed a few versions of an adapter plate in PLA for various grills; however, it's not quite right to claim that they won't melt.
First no one claimed "that they won't melt".
Second, I SPECIFICALLY said NOT to use PLA. My PETG printed plate, or one printed from ABS, works fine. And although the highest temperature longer cook I've done was holding 400°F, it has not suffered from MUCH higher temperatures during full-open burn-off to clean the heat deflectors and grill surfaces.