As many pointed out 2003 Supported was removed in Data Protection Manager 2012 R2
Steve found a public annoucement that its on its way back
“Hello Folks, I am the GPM for the DPM product group and sincerely apologize for this. Not supporting an already supported server OS for back-up is DPM 2012 R2 was a mistake. We are fixing this in the next update roll-up for DPM scheduled to be released shortly. Thanks for your patience.
This is good news as Data Protection Manager wont hold down a suite upgrade all the way around , ITS NOT A FREEE PASS to keep goofing around with 2003 servers , they are close to end of life , upgrade/migrate/power off but until you do at least we can soon again protect 2003 workloads with Data Protection Manager 2012 R2
Now go off and migrate