That’s a good catch, but don’t modern CPUs thermally throttle, rather than risk damage? Not that you should rely on this with an underpowered cooling solution but I would expect worse performance, not a fried chip.
There thermal paste on the whole CPU in TFA, it's just thinner on one side because there was more pressure there. Or are you looking at the pic of the heat sink, which is larger than the CPU heat spreader and thus only partially covered by paste?