There is nothing about thorium that makes it able to be stopped immediately or run at much less pressure. There are reactor concepts that run at lower pressure and have passive safety when shutdown, but they could use thorium or uranium just the same.

Thorium reactors have to be part of a closed nuclear fuel cycle meaning you have breeder reactors combined with fuel reprocessing. No nation seriously does this right now because when you reprocess you can easily separate bomb materials (although India is allegedly moving towards a closed thorium cycle). Reprocessing involves nasty chemicals that are super radioactive too which is another step where things can go very wrong.

Also, thorium can't even run a reactor by itself. It has to be used as a feed material to breed Uranium-233 by absorbing neutrons and decaying, so at the end of the day you are still using uranium to produce power. The only advantage of thorium is that it doesn't produce as many actinides which are the really long-lived radioactive waste products. So after thousands of year the radiotoxicity of your waste is less with thorium than uranium.

I'm pro nuclear. I like thorium, but it would realistically require a nation to step up and invest trillions of dollars in the infrastructure and licensing only to have things rolling along decades later. Although, it would provide energy for a few centuries if done well.