Best to withold judgments until get more of the facts are revealed.
However, it came to light that their internal research found most people drink the coffee while driving. The primary reason has been speculated but of course never officially acknowledged as what you suggest.
It sounds like that might not be accurate:
>...In 1994, a spokesman for the National Coffee Association said that the temperature of McDonald's coffee conformed to industry standards.[2] An "admittedly unscientific" survey by the Los Angeles Times that year found that coffee was served between 157 and 182 °F (69 and 83 °C), and that two coffee outlets tested, one Burger King and one Starbucks, served hotter coffee than McDonald's.[37]
https://en.wikipedia.org/wiki/Liebeck_v._McDonald%27s_Restau...
I'd like to note though that what ever the case, a beverage that she was expected to put to her lips managed to give her horrific burns. And there was, if I recall correctly, quite a few of the same case accident reports at Mcdonalds on record. She was the only one who ended up in high profile litigation though. I suppose my point is that she wasn't silly or unreasonable as the slow drip feed of facts led many people to conclude as they heard it.