Unless you like your pizza black on the bottom and white on the top, a piece of aluminium is about the last thing you want to use to cook pizza on a grill.
While I agree 100% that aluminum is a poor choice for a grill hearth, we don't really know what the instructions for this pan are. It could instruct the user to bake the pizza in the pan, without a reheat, like a typical pan pizza. If that's the case, you wouldn't see an overly charred undercrust and a white top crust.
Also, there's a thermal mass component here. Visually, this feels somewhere between 1/8" and 1/4" thick. Even if there were no instructions and someone cranked their grill to a 600ish pre-heat, the amount of thermal mass probably wouldn't be sufficient for a black undercrust. 1/4" probably not, 1/8", definitely not.
I'm definitely in no way recommending this pan, but I do think the reasons not to purchase it could be a little more complex than a massive heat imbalance.