An age limit of 60 should be the age limits for presidency examples are pmb and trump.these are the reasons.

1.People of age behave like children are usually easy to influence to make the wrong decision based on advice of people they view as their favourites just like children.just like d cabals in abuja and washington dc a selected favourites of this old presidents.

2.There policies are old school e.g in a rapid changing world of global weather change and borderless global markets where no nation is truly independent of each other.donald trump is scraping global warming policies that keeps global warming in check and pmb is making nigeria a rice growing independent country where we dont have comparative agricultural advantage unlike yams,cassava where nigeria is d highest producer and have comparative advantage


3.They tend to be stuborn when making decisions and dont listen to the voices and reason with the voices of their fellow country men.


4.They tend to favour isolationist policies. e.g like banning of importation,tough immigrations laws,building a wall across mexican and u.s.a borders,banning importation of cars through land borders.etc
Feel free to add your own

u have a point.... That of PMB and Trump are just accidental and exceptional....

i tell u