Under-seat Subwoofer safety concerns

[Hatchy Zoom]

So I was going to install a subwoofer under the driver's seat of my little Mazda2, but I just came across this paragraph in the user manual:

Do not place luggage or other objects under the front seats:
Placing luggage or other objects under the front seats is dangerous. The components
essential to the supplemental restraint system could be damaged, and in the event of
a side collision, the appropriate air bags may not deploy, which could result in death
or serious injury. To prevent damage to the components essential to the
supplemental restraint system, do not place luggage or other objects under the front
seats.

So, according to Mazda, placing anything under the seat can be dangerous.... Any feedback on this, guys? What is one to do? Is a trunk/hatch subwoofer the only safe sub option here?