Definitely sounds like a possibility.
However, then there’s the possibility that it would add to the already present problem of the old ‘Add X infantry to my capital stack’, prolonging the waiting game of capital grabbing.
Potentially it could make the game drag out, in that case.
Perhaps a defensive bonus would be appropriate, if it were to apply to a limited number of units. Such as, a +1 defensive bonus to a number of units equal to the IPC value of the territory? Half the IPC value of the territory?
Or that activating the special homefield advantage cost a number of IPCs, in effect giving the player the option of using it, -or- adding more infantry, weighing the advantages of both, but not using both?