So, to clarify, your comment "IF the different cultivars were cloned..." (my emphasis) wasn't in response to someone else in the thread stating that they are all clones. But you ARE suggesting that all were clones of a single plant.
If you read the wikipedia page on it:
https://en.wikipedia.org/wiki/... (which is where I believe you got your info regarding Compton), it states that at least two other people were cultivating the hybrid before Compton, so there would have been multiple plants being cultivated not just one.
It also states "natural occurring hybridS" which suggests that the hybrids were not all the same variety/cultivar in nature, but that they varied (likely based on location). So that makes it potentially reasonable that some of the currently existing cultivars for sale came from naturally occurring variations not from the Compton plant.