Yes, the comic feels like it was taken out of SMBC, had its humor removed, and stuck on XKCD. That's not a problem, really, it's not like SMBC should, or does, have a right to this sort of "best case / worst case" joke. But SMBC does have a fairly unique style in terms of being completely mean spirited, as in this best case/worst case comic [i would thank the poster who posted it but it was anonymous...]. XKCD can't really make up its mind on this. Is it all sweet and sad etc, at times, but at other times just plain evil. It leads to a sort of webcomic personality disorder, where not only can we not recognize a stick figure as being distinct from any other, we can't even know the sort of way that xkcd stick figures usually act.
Usually, with a character, you are given some cues about them - even if it's the first time you are meeting them, you see their clothes, say, or their hair, or the way they talk, the words they use, etc. And this is good, and important. because in order to care at all about the characters you have to know something about who they are, what they think, how they respond in certain situations.
But in xkcd there is none of that. There's just - stick figure. usually a plain stick figure is a man, but that's all. We don't know a damn thing else, ever, and in my opinion, that leads to forgettable characters. Does any other popular webcomic have these two features? No running characters (ok, besides the played out and one dimensional Mr. Hat) and no visual or verbal cues about them?
Anyway, I know I didn't say much about the comic - I'll leave that to the physics kids. But take this rambly essay loosely inspired by the comic in its place.