You are wrong. Dominant just means there is no super form in the snake realm. Dominants act just like Co-dominants, just no supers.
Comparing a Super Pastel to a Spider even genetics wise is way off.
Pastel is a co-dom gene. When the snake has 2 Pastel alleles it is then a homozygous or super pastel.
Spider and Pinstripes are considered dominant, because there has not been a visual super Pinstripe or Spider produced.
Spider x normal
S n
n Sn nn
n Sn nn
Sn= Spider
nn= Normal
SS= does not exist.