Would not think that a Fire extinguisher is so likely to be discharged by mistake. They should be stored in a bracket with a clamp to hold the extinguisher securely in place. Often the bracket is in a nook that is out of the way and less likely to be hooked by a strap or impacted in some way that would discharge it.
The risk is also related to the type of extinguisher. Powder makes a mess when used, but as an escape tool, who cares. As a random event that is an accidental release, one of the Haylon replacement gas type extinguishers results in a much better outcome. If concerned with the safety of your storage location, an investment in a better extinguisher might be advised. Certainly upgrading to a bigger extinguisher has value to consider in the review.
Travel Safe and with a Smile! Pat