I'd worry about that no matter what. I mean even if a big name in the industry wants my snake, how do you know they'll treat it well? Even if I gave a snake away to a friend or someone else as a purely pet gift, who knows what they'll do with it in 1, 2, 5 years. They might give it away to someone who doesn't care, they might stop caring themselves, or maybe they'll get tired of it and just release it when it can't survive in that location.
Have you used co2 on a snake before? I can't find anyone that has because they all say that snakes don't react to the co2 the same way, they use way less oxygen but have a similar reaction to too much co2. If you give rodents too much co2 they hyperventilate and suffer while they die. This doesn't really last long for the rat, but it takes much longer on the snake, hence the inhumane.
I wish that co2 was the most humane way so that there's a simple and easy way to end a snakes suffering, but the fact that no one does it tells me something. Especially when the two ways it seems like everyone does it is either expensive (vet injection, not to mention the horror stories of how this goes) or it's gruesome (destruction of the brain), why would anyone do either of those if they could use the co2 chamber they have for rodents?