[Or perhaps the third, best option: he's a huge nerd.]

Not personally, no, but I have studied many quadrupedal species with this body plan before -- that is, six-limbed with a humanoid torso where the neck would be on a four-limbed animal. When you travel as much as I have you eventually will have encountered beings with every conceivable body type and then some.

[That and also he's an avid roleplayer and, like many roleplayers who are also scientists, wanted to make sure the stupid fantasy creatures in his stupid fantasy tabletop game actually made sense.]

Not that I thought I would ever be able to experience it personally, of course. Talk about a unique research opportunity.