You will note the discussion was about gunpowder (I’m assuming in the classical sense). And to say that a force is not created by igniting the powder within a compressed space with one avenue of release (bullet down the barrel) isn’t an explosion is wrong.
Powders used back in mining days definetly yes. But in a gun, todays modern powders only burn at an incredibly fast rate. It takes an awful lot of continuous “push” for a projectile to be sent out of a long barrel. Theory is this. The heavier the projectile and the longer the barrel, the more push is required for it to make it to the muzzle. All powders burn at different rates for this reason.