The notion that moles on the palms, soles, and genitalia are more risky than other moles is tradtional, not supported by data. The fact that a mole is repeeatedly traumatized is likewise not a reason per se to remove it. Finally, excising a mole from the sole of an infant is not a trivial matter--it may indeed scar, which can be painful and irreversible.
My advice is to seek the opinion of a dermatologist, perhaps someone with a special expertise in melanoma, if there is someone in your area, perhaps at a teaching hospital.
I'd wager that the consultant will recommend photographing the lesion but otherwise leaving it alone. In any case, you'll feel more relaxed about the mole if you get that kind of expert opinion.
Best.
Dr. Rockoff