it rides off of the "kids dont lie" saying, which is to say that they havent quite yet figured out the notion of not speaking their mind to protect your feelings, it doesnt mean theyre these eternally smart oracles who speak OBJECTIVE truth
the "totes smart perfect innocent child pwnes the stupid adult with his childlike wisdomz" is an age old trope, its why people use children as soapboxes in the firstplace
in order to do that, they need to be portrayed ass perfect little angels
if the kid actually behaved like a kid, him saying "we need to abolish capitalism and sieze the means of production" wouldn't hit quite so well, if it then immediately follows it up with "AND ALSO BAN ROCOOLLI YOU FREAKIN FREAKS!! EVERYONE WHO EATS IT GOES TO JAIL FOR A BILLION YEARS!!!" *kicks you in the shins*