It's more likely a similar reason why you would let a cut of meat rest after taking it off heat. It allows the heat to even out and finish cooking.

I don't think you can successfully sue over mildly burning your mouth. What loss can you claim?

The woman who sued mcdonalds for handing out cups of boiling coffee, required significant skin grafts after she got third degree burns all over her genitals, and was asking for her medical bills to be covered.

Mcdonalds, having been told multiple times to stop serving boiling coffee after other people got severe burns, got slapped hard, and has been trying to frame themselves as the victim so that they can't get sued for burning people's genitals off ever since.