Pesticides are routinely used in modern forestry operations, the most common use being herbicide application to eliminate unwanted vegetation in an area that's being managed. Some of the trees killed by herbicides might be used for firewood if they're large enough. The pesticide manufacturers state that the chemical composition of their products is safe and breaks down with exposure to the elements but there is the possibility that the knowledge is incomplete - for example the widespread use of 2-4-D in forestry operations, often being sprayed from airplanes which included Agent Orange in Viet Nam with subsequent health effects on humans and ecosystems. And the World Health Organization recently linking 2-4-D exposure with cancer.
If pesticide use results in ill effects, then use can't seen as ethical. Organic might mean that the wood was harvested from unsprayed land, or it might be targeted at bumping up sales to a pesticide-sensitive market.
The Ontario government recently outlawed cosmetic use of pesticides on private lands in an effort to reduce harmful effects so with consumers being well aware of this together with the success of organic marketing, for example people shopping at Whole Foods and buying organic and ethical product only, maybe it's understandable. I've seen some pretty agitated residents complaining that their neighbors were spraying pesticides, esp with kids present nearby possibly being exposed to spray drift.