The thing you should understand about hypotheticals is they're not a substitute for the equal sign. When I present you with the hypothetical "why make murder illegal," I do not mean to suggest that !(proscribing account sales) = !(proscribing murder). There are, indeed, differences.

The text you have quoted was a response to TL;DR: "account sales are a necessary evil, better than they happen here than elsewhere."
If you feel that account sales are desirable, like gun sales in your example, feel free to explain why.

That said, a forum created to advance Bitcoin is not necessarily the best place to sell guns.
Or to double as an online scam bazaar.
Or as a casino.
Or as an MLM ponzi promotion vehicle.
Or a banner ad platform.

If you & thermos didn't, in all your wisdom, endow it with all these trappings of petty scumbaggery, account sales would not be an issue.
See how you can solve a problem by thinking outside the box?