There are LF silkies - they just aren't common, and they can not be shown
Sizzles can be shown in the silkie class. You don't say frizzled silkie because it means something different.
For example:
This is a male frizzled silkie I own.
and this is a male 'sizzle' I own - many generations into the project. He processes all the proper silkie traits, and is the grandfather of the silkie behind the frizzled silkie, and is the father of the frizzled silkie (which is also called a frilkie).
Note that he has no tail feathers due to bullying here
but you get the picture... He's practising his flamingo stance.
Why is it that you prefer LF silkies anyway? You can get breeder culls that are too large to breed. Silkies are the biggest bantam. They are around 3.5-4 pounds for males.