You're wrong.
None of the Bronner's soaps contain a preservative. You picked the only product they have that does not use EOs for scent (therefore the only possible one that could have hidden Naticide) and claimed that Natural Almond Fragrance=Naticide, when it is likelier* (natural) benzaldehyde (proof below).
Their soap ingredients:
Peppermint:
Water, Organic Coconut Oil*, Potassium Hydroxide**, Organic Palm Kernel Oil*, Organic Olive Oil*, Mentha Arvensis, Organic Hemp Oil, Organic Jojoba Oil, Mentha Piperita, Citric Acid, Tocopherol
https://shop.drbronner.com/pure-castile-liquid-soap#scent=Peppermint
German (for reassurance that they aren't bypassing any loose laws from the US):
Aqua, Potassium Cocoate (Verseiftes Kokosöl*‡), Potassium Palm Kernelate (Verseiftes Palmkernöl*‡), Potassium Olivate (Verseiftes Olivenöl*‡), Glycerin*, Mentha Arvensis Oil (Ackerminzöl), Potassium Hempate (Verseiftes Hanföl*), Potassium Jojobate (Verseiftes Jojobaöl*), Mentha Piperita Oil (Pfefferminzöl), Citric Acid (Zitronensäure), Tocopherol (Vitamin E), Limonene◊
Lavender:
Water, Organic Coconut Oil*, Potassium Hydroxide**, Organic Palm Kernel Oil*, Organic Olive Oil*, Lavandin Extract, Organic Hemp Oil, Organic Jojoba Oil, Lavender Extract, Citric Acid, Tocopherol
https://shop.drbronner.com/pure-castile-liquid-soap#scent=Lavender
German: Aqua, Potassium Cocoate (Verseiftes Kokosöl*‡), Potassium Palm Kernelate (Verseiftes Palmkernöl*‡), Potassium Olivate (Verseiftes Olivenöl*‡), Glycerin*, Lavandula Hybrida Oil (Lavandinöl*), Potassium Hempate (Verseiftes Hanföl*), Potassium Jojobate (Verseiftes Jojobaöl*), Lavandula Angustifolia Oil (Lavendelöl*), Citric Acid (Zitronensäure), Tocopherol (Vitamin E), Coumarin◊, Geraniol◊, Limonene◊, Linalool◊
Almond:
Water, Organic Coconut Oil*, Potassium Hydroxide**, Organic Palm Kernel Oil*, Organic Olive Oil*, Organic Hemp Oil, Organic Jojoba Oil, Natural Almond Fragrance, Citric Acid, Tocopherol
https://shop.drbronner.com/pure-castile-liquid-soap#scent=Almond
German:
Aqua, Potassium Cocoate (Verseiftes Kokosöl*‡), Potassium Palm Kernelate (Verseiftes Palmkernöl*‡), Potassium Olivate (Verseiftes Olivenöl*‡), Glycerin*, Potassium Hempate (Verseiftes Hanföl*), Potassium Jojobate (Verseiftes Jojobaöl*), Parfum (natürliches Mandelaroma), Citric Acid (Zitronensäure), Tocopherol (Vitamin E)
As evident, they use nothing of the sort.
*Now to explain why it is likelier benzaldehyde than Naticide:
First, why would they preserve their Almond scent but not the others? Second; before the label wording change, which was likely done for customer appeal (natural almond fragrance sounds better than benzaldehyde), the below was the label-benzaldehyde is visible. And third: Naticide can be labeled as Fragrance or Parfum, but probably not something as specific as Parfum (Natural almond fragrance).
LS as is and by itself requires no preservation, data from the global sales and success of this (and others like it) product would suggest. Quite right about the fact that consumers may wrongly use the product and create a need for preservation, though.