Your suggestion is a bit confusing.
Do you want the conditional solid only for the pathfinder behavior or for the solid behavior itself ?
Anyway, add something like the custom movement behavior or 8direction as well as the solid behavior to your enemies and they will "push themselve away" automatically (since I guess what you are willing through this suggestion is to get some flocking/enemies not overlapping).
Otherwise, you can already disable the solid behavior and so in certain conditions you could either chose to enable or disable it according to the specific logic of your game.
The pathfinder behavior itself does not handle the collision with solid anyway.