I figured it out.
The mb has a function in it's bios to redirect the preboot screens out the console port. There are three options on how the board should handle this. When set to two of the options the NanoBSD build for some reason pauses if there is no console cable attached. I am assuming that the BIOS still has some kind of handle on the com port and the ttys driver is in a wait state. When I plug in the console cable the mb releases it's hold on the com port. If I disable post boot console redirect then NaonBSD does not get hung.
I have placed a bug report with Supermicro and all is well in my world again.
Thanks