Unintentionally funny thread title.
I'm not sure I understand the "morally wrong" piece.
If I sell packs of Rizla's or Zig Zag's, is it OK to sell them only if a customer plans to roll and smoke tobacco, and wrong if they intend to roll something else? In any event, I don't see how it matters at all, as long as they don't plan to roll or smoke in your shop... do car salesmen fret over the idea that their customers may one day use that Hyundai to speed or run a red light?
The Friendly Stranger and Toronto Hemp Company (THC) have been around for a couple decades. They seem to have avoided LE by being discreet with end-use descriptions. I recall a friend getting kicked out of a shop in the 90s because he kept saying "pot" instead of "smokeables" "tobacco mix" or "herbal mix" (et al).
At-present, the 3 closest convenience stores to my house all sell paraphenilia (herbal grinders and all forms of glassware). As long as you're not selling to underage people, it seems like you're fine.
If I'm buying paraphenilia online and the site isn't discrete, I won't use them. I also prefer to buy in Canada to avoid any potential customs hassles. I also try to avoid travelling with paraphenilia, even unused.
Unless you are looking for something incredibly specific and unavailable at your local, a brick and mortar head shop is the way to go, in-particular with glassware. It's never fun to get a broken piece in the mail, and photos never do glassware justice, in-particular if it's a unique piece.
I use Amazon to replace parts as-needed for my desktop vape, and portable vapes I have bought and have shipped over borders.
I believe a big part of the Chong conviction was over a couple of the places (states) he was selling his bongs (or how he was bringing them into the state) and the lack of discretion in his advertising / marketing, in-addition to being a high-profile company owner (similar but different to Marc Emery owned dispensary raids in Toronto).