More like an absurd oversimplification of a generalization. Few people really revert back to what's perceived as childish when in reality it is more akin to taking a step back and finetune your reaction based on the lessons they gathered throughout their lives.
In today's era most people have lived way too comfortably so it might skew your perception of this based on the oldies of today. Having lived through less major issues like not having access to clean running water during their earlier years or something less obvious like access to good painkillers. Imagine having to tank every single headache in your whole life, that'd probably change you deeply.
On that note you might be right for different reasons, Aesir is a hundreds years old immature brat because there's no way such an OP character faced anything so 'character building' in all his life. I'll take it that way everytime a character is dumb for its age, from now on. Either that or incompetent and/or lazy writer
