As to creationism not being good science, that would depend on how good science is defined. I contend that non-creationism suffers from the same charge for the same reasons that many use against creationism. To admit matter and energy exist and then to limit reality to matter and energy is neither warranted nor logical, but it is a philosophical/religious meta physic. When science is limited to those things that are observable, repeatable and verifiable it must remain silent on origins.
Further, to contend that God could not create a universe with the appearance of age is not science but a theology that limits the omnipotence of God.
As to your contention that creationism is not an essential doctrine to salvation, does nothing to refute the contention of creationists that is an essential doctrine for fulfilling the dominion mandate and the advancement of the kingdom. If you will not believe the words of the king, it will be difficult to trust His propitation, follow His law or walk in His Word. Perhaps not an essential to salvation, but a determinate for a fruitful life.
Creationism claims that it is scientifically valid. You seem to be arguing that there are NON-scientific reasons for supporting the idea of creationism.
Creationism claims to be scientifically valid. If the only reason for supporting it are non-scientific reasons than this argument itself undermines Creationism. It’s either scientifically valid or it isn’t. If it isn’t scientifically valid and you nevertheless accept it as an article of faith then it doesn’t really do for us what Creationists claim it does, does it?
I appreciate your position but I think it’s problematic.