AHAHAHAHA.
First off there are a few things wrong with your dudes "logic", if I can even use that word. NOTHING release a gas when it saturates with a liquid. A gas is release when something is heated, aka water to vapor or dry ice to CO2.
Secondly if aspen does release any gases when heated it is not deadly or causes damage to the snakes that live on it.
NOW pine and cedar woods to release a toxic gas when heated up along with being known for it's more dusty nature causes RI's to death to snakes and health problems in most small mammals.
Though BP's don't naturally crawl around in aspen chips all day in their natural habitat it is one of the better odor controlling woods allowing it to look pleasing to the eye and giving the snakes the chance to burrow like they are known for doing.