I recently discovered that if you sell things to a shop owner, and then kill said shop owner, he/she drops everything sold to them allowing you to pick up everything, leave the area and resell the same gear when they refresh with full coin in their til.

I assume you could resell it, I didn't try because of that exploiting a bug rule.

I'm ok with killing shop owners so a new guy can get a loan and buy the business, but is them dropping with everything a bug? I ask because their specific list for sale doesn't remain with the corpse, only what they've purchased.

This isn't true in the general case. More info would be helpful.

I think it's more a matter of that he hasn't TRIED to do it, but thinks it's possible. I advise him to try it sometime, he'll quickly find out why. Also, Imms can correct me if I'm wrong, but they're generally cool with you TRYING to see if your suspected abuse works before mentioning it, so they're not having to check up on suspicions. It's the rampant abuse of such that gets you in trouble.