Is A3 meant to have connecting links horizontal through it's path?

Another bad idea: build a simulation-world to live in so that we don't actually have to worry about real-world risks. (disadvantage - is possibly an X-risk itself)

It kinda depends on which x-risk you are trying to cover...

For example - funding technologies that improve the safety or efficiency of nuclear use might mean that any use is a lot more harmless. Or develop ways to clean up nuclear mess; or mitigate the decay of nuclear radiation (i.e. a way to gather nuclear radioactive dust)

Encouraging people to start small bio-hack groups around the world could improve the biotechnology understanding of the public to the point where no one accidentally creates a bio-technology hazard. Developing better guidance on safe biotechnology processes and exactly why its safe this way and not otherwise... effectively "raising the sanity waterline" but specific to the area of biotechnology risks.

(I suggest that maybe you want to offer to take free suggestions before you pay people - at least that might save you some dollars)