this post on cetyl alcohol. Neither cetyl alcohol nor stearic acid are considered emulsifiers in any way. They are considered to be oil soluble ingredients, like our oils or butters. They have a required HLB value, meaning they have a value that helps you figure out how to emulsify them into your products. If you want to make something - let's say an "oil free lotion" with water, cetyl alcohol, and preservatives, you will need an emulsifier to make the water and cetyl alcohol combine into one phase instead of separating into two different phases of oil and water.
As an aside, do you notice that OH at the end of the carbon chain in cetyl alcohol? This is how we know it's an alcohol! It isn't called an alcohol because it's a watery substance that makes it easier to talk to the opposite sex - it's called an alcohol because it has that hydroxyl group at the end of the chain!
click here for the attempted duplication - you'll have to find an emulsifier you like so the cetyl alcohol isn't just floating on top of the water phase in the bottle. Cetyl alcohol behaves like our oil soluble ingredients, meaning it won't create a homogeneous product without an emulsifier. (If this product isn't separating on you, they aren't giving us an accurate ingredient list.) And when we consider that to call something a conditioner we need to use a positively charged emulsifier, we might want to choose a positively charged emulsifier that will offer substantivity. I wonder which one that might be....
(Hint: Look in the hair care section for the topic of substantivity!)