Looks like I was dead wrong here- turns out there’s another JC tweet that says: “If you use a weapon in a way that turns it into an improvised weapon—such as smacking someone with a bow—that weapon has none of its regular properties, unless the DM rules otherwise.” So bonking people with a crossbow wouldn’t count for GWM because the crossbow isn’t heavy when you’re not shooting it
Cool! So if you go to a restaurant, order mac and cheese, get it in a cardboard container and when it spills you get hospitalized for a week, do you say “mac and cheese is meant to be served very hot! Of course I’ll cover the medical bill myself!”. What about when a few dozen people run into the same issue, because the restaurant has figured out that the occasional lawsuit from people being badly injured is cheaper than the cost of keeping the mac and cheese at an edible temperature? I mean, consider the comparison you’re going for here. “If she’d heated a substance to that temperature herself, then spilled it on herself, it would be entirely her own fault! Why is it when someone else heats a substance to an unsafe temperature, then someone gets injured by it, it’s not entirely on the injured party? They should know that the substance was heated far beyond what anyone would reasonably expect it to be provided at!”