The civil war was never “legally declared” an insurrection and yet the amendment DID bar Insurrectionists from holding office. The Constitution does require it.

People under 35 are not eligible to be president. As far as I know, nobody under 35 has been able to get on the ballot to run for that office.

That said, your points are credible and interesting. Especially in the current context where insanity and cruelty is king.