AiG did not reference Chapman's monograph. It stated,
The closest thing to the claim which launched our pursuit of this whole trail is where Slijper states, ‘Thus, at Ayukawa Whaling Station (Japan), a Sperm Whale was brought in in 1956, with a 5-inch tibia projecting into a 5½-inch “bump”,
even though other sources (like Chapman) say the limbs can be 4 feet long.
Here is a discussion of whale evolution and embryonic growth: See esp., page 452 Note that whale embryos have hind limb buds, which disappear before birth. It makes sense that ocasionally the mechanism that causes them to disappear fails, leaving the adult with tibia, metatarsals, etc.
Why no photos today of whales with legs hanging off of them?
The TO article has photos of the bones. Chapman's article is not on-line, I don't know if it included photos or not. I can't find any on line.
We know that there are bones within a whale that help with reproduction. Why could this bone not be just an overgrowth of that bone? Oh, I know, because some evolutionist museum journal said so.
Evo or not, I'm reasonably confident that Chapman and colleagues could tell a pelvic bone from a leg bone. They are very different shapes.
The question remains, why do whales have the genes necessary for hind limbs if they were 'designed' for the water?