But it's likely a script like this stabilizer will still be useful,..

It is actually going to be part of the blockchain coding.

Here is a write up of what how it will work:

https://gitlab.syncad.com/hive/hive/-/issues/129

It is not going to be a money maker per se. As you mentioned, the goal is to put a cap on the price of HBD and remove the incentive to push the price higher.