Strength effect caps at +2 fear, it's not a big deal.
For reference, holding a gun (sling counts) is +6 fear (only +2 if the NPC also has a gun), sapiovore mutation is +10, grotesque mutation is +9.
Unless you have sapiovore or deformed, just unequipping all weapons before the NPC spawns (it has to be at spawn time, not talk time) will do more than strength could.