Yes, that is wrong. That nut is a F-style nut! Email PB and let them know. They possibly do not have the G-style bone nuts (as there is none available online, I'm also waiting for one!).

You can proceed with your build using the plastic nut and put the bone nut in at the end of the build.

BTW - That spalted maple top looks great. It has a nice pattern over the whole top. Good score! The neck also has some patterns.