Bug abusing is a low-morality act, it’s undeniable. Especially if it is doing harm to over players.
But it is simply using the game as it behaves.
The azerite snake/alexstrasza interaction was a bug. But it was allowed. Some streamers asked blizzard if it was ok to play the deck in stream and make videos about it before it gets fixed and the answer was yes, it’s ok.
The faulty one is the game here, not the player. If they didn’t want that interaction to exist, they shouldn’t have allowed it to exist in the vanilla game to be replicated by anyone. Same for the weapon. You cannot punish players for doing something as simple as playing the game. If you do, you will punish players that did not intend to bug abuse and that simply found out this issue by accident, which is unfair to punish them because of your mistake.
There can always be a scale for if you really want to punish bug abusers, but it generaly only happens when the bug is causing serious damage.
Cheating however, the faulty one is definitely the player. They intend to cause harm to other players, regardless of the mean, but one that is not part of the base game. They use third party whatever to accomplish something that is not of the responsability of the game.
As GnomeSayin said :
From there you just have to draw the line to when it becomes cheating.
For me, players using modified decklist allowing them to play a 0 mana soulfire should be banned for cheating, since this is not something you can do in the base game.
But I guess they either don’t care when it’s only happening for a tavern brawl once in a while, or they consider that banning it could bann players that just google “X tavern brawl decklist” and got that one without knowing it was not a legal one (how could they know the decklist does not come from the game, if it works in the game ?)
tl;dr : bug abusing and cheating should be clearly separated, would it be for case clarification. The consequence for each could be the same if it was the policy, but the real debate is to which category each case belongs, and where you put them on the spectrum of each