i think you have to consider worst setup violation bcos DC by default does not optimize the remaming parts of a design if critical path is still viloating timing(hence subcritical path is not optimized).
If you do not fix the hold your circuit will not work at all (Hold requirement does not depend upon frequency). If your have setup fails then still you can work at lower frequency.
So the flow is
1. fix the setup within your project shedule as much as you can
2. Finally signoff with all the hold fixed.
Anyway if system point of view both are important than fix both.