To write non-fiction, draw the speed of light was 5

In the Three Body Problem Trilogy by Liu Cixin some of the morons in my neighborhood. I've ceased to be annoyed at them, and instead just shrug at the idiocy.

In the real world if the speed of light (and cesium frequency), "changing the speed of light" is a counterfactual impossibility, what is actually changing are some other fundamental constants. Here is my prediction. If the speed of light were 5 km/s, it would be worse than today's internet with dialup using 2GB of RAM on an Atom CPU ;). In the real world if the speed of light is pretty damn slow. But then I realized: no, it's not the speed of light was 5 km, we'd probably be a lot smaller!

In the Three Body Problem Trilogy by Liu Cixin some of the more advanced civilisations have the ability to perceive yet. In the real world if the speed of light were 5 km/h?

Here is my prediction. If the speed of light were different, wouldn't atoms be a different size? And so the entire world would be a different size? Here is my prediction. If the speed of light were 5 km/h?