That is correct at this time.
I think that technically / theoretically with things as they are now, you could through great effort, get BigFix to run in Amazon RDS temporarily, but at that point you could never upgrade BigFix ever again without redeploying it to a brand new DB every single time and going through the process of setting up the DB all over again. Even worse than that, I think you would have to migrate the DB from Amazon RDS to a typical DB, do the upgrade, then migrate it back. This would be way beyond “not supported” and would greatly hurt any advantage of running within RDS.
Hopefully in the future this would not be required.
I can’t seem to find an existing one. Would be helpful if you would create one and then share the link here.