Let’s not forget: it appears that JD Vance may be the originator of that whole farce.
In which case, Trump touted it because either a) they honestly think it is good propaganda which will sway the campaign, or b) Trump is quite literally eating his own dog food, because there are too many lies to keep track of.
That plus a massive amount of inherent isolationism plus an extreme birth shortage and an already very aged population.
The writing is on the wall in many ways unless major, unprecedented changes were to be made. Japan in a hundred years will be unrecognizable without them.