I want to be able to direct a section of my flip sim to avoid an area. Would it be best to use pop curve force and port that into either the velocity input or maybe plug it into sourcing of the flip solver. Or is there a better way?

Avoid using the sourcing input for force redirection. The sourcing step in FLIP is primarily designed for injecting new particles or adding a one-time initial velocity volume at birth, not for steering active simulation particles.

There are a couple of available options:
As you mentioned use a pop curve force. This might be best if you're aiming for a guided flow.

If you just want particles to completely avoid a specific area / volume (like an invisible boulder or a dead zone), don't use forces at all. Use a Static Object or standard collision volume, and make sure it is invisible at render time.

​If you want particles to actively 'run' away from a specific area, a POP Attract (with negative force which basically turns your pop attract into a "POP Repel") with a bounding box/spherical mask might just be it. I think that would be incredibly efficient.