20 years after the founding spider was sold a homozygous spider is also not publicly proven viable.
Hard to say which side the burden of proof should be on. I'm of the opinion you should at least consider the possibility that everything is lethal and/or can't reproduce until proven otherwise. A homozygous lethal morph might be very hard to prove.
With woma it wasn't so hard because the pearls looked so different it seems clear that they are the homozygous animals even though they don't live long enough to breed and actually prove they are homozygous womas.
With spiders we don't know if the homozygous spiders just die early in the egg development or incubation process or if they are fine and look just like regular spiders but not enough have yet been produced and bred to prove one homozygous.