https://www.reddit.com/r/hashgraph/comments/9d38ek/how_does_hedera_know_2n3_in_the_mainnet/

The 1000 nodes is just an example which is qualified by a further requirement that it holds atleast 1/3rd + 1 of the total currency by value and that these 1000 nodes are somehow stuck. This will ensure that the network stalls. It can be even lesser than that number. One cannot have any protection against this 1/3rd + 1 because they could be colluding — for whatever reasons.

Again, it does not matter that if the nodes are in one region or another, because of different types of collusions that may be possible.

For instance, Jeff Bezos may ask his VP to shut down all Hedera nodes across all regions of AWS. What in the design of Hedera Hashgraph will keep it going?

The design is at fault and nothing can be done to fix it as it stands.