A modulo is taken during the routine. No joke. I looked at it, and when it is calculating the palette slot of the palette slot byte, it goes [palette slot byte] % [0xF] = [Upper Half of Byte]. So, yeah, the 1X makes no difference.
I noticed, that after it went through and loaded all of the standard palettes, it went back and reloaded palettes 1 and 0 into their proper slots. Maybe there is a secondary palette table????????? This table may not have been expanded, so it causes an error and the palette isn't loaded. I wish I had more time to do research since this topic intrigues me.