You can use pose.scores or this: pyrosetta.rosetta.core.io.raw_data.ScoreMap.get_energies_map_from_scored_pose(p) to grab a dictionary for all the scores. Generally, you want to output a scorefile or equivalent and tie the PDB to the scorefile instead of having the total score in the PDB. Yes, the function you found prints out a lot more information – but that is the standard way of outputting all the data. You get a pose residue energies table, a table with all the scores, and whatever extra data is added during a protocol.
Typically in pyRoseta, you can do it yourself to output a JSON file from a dictionary that you get from get_energies_map_from_scored_pose().
You can also use the toolbox function: pyrosetta.toolbox.py_jobdistributor.output_scorefile()
Finally, a PDB file is simpy a text file. If you really want ONLY the total score in it, just read the PDB file and append a line with the total_score using in-built python IO.