Unless I'm missing something, my tests suggest the D72 doesn't support programming at anything other than 9600. The COM Port->Baud rate option (menu 331) only has options for 2400/4800/9600, and setting anything other than 9600 there still results in CHIRP auto-detecting the baud as 9600.
This is the APRS/TNC baud rate, not the one for the PC, AFAIK, so it's unrelated. Since the D72 uses a USB port for the PC connectivity, it's possible that it will just speak to us in whatever rate we try first, which might mean we're currently auto-detecting something slow. I'll try to get my hands on a D72 soon and see if I can poke around a bit.
I can't imagine that the D700 from yesteryear can do 57600 and a modern HT like the D72 is limited to 1980s baud rates :)
--Dan