I think we agree on most points. Long term inbreeding for more than necessary to prove something is a bad idea. Outbreed whenever possible.

Idk about the so-called "defects" being caused by inbreeding. There are genes known as "activator genes" or something like that, which activate whole other groups of genes. So maybe the spider morph (example) is one of these activator or switch genes, which activate both the pattern mutation AND the wobble and there's no way to separate them because the only gene we can work on is the switch gene. Scientists have switched a single gene on a fly and caused legs to grow where antennae should grow! Switch genes are though to be the main difference between humans and chimps.

That may be right on some of the others, though. Duckbills certainly aren't linked that way.

In this case, he's just trying to prove a trait, so I say go for it.