Edit: thread title needed to be more specific: "Would it be morally fair of Nexon to ban buyers/sellers of NX under the following circumstances?" would be more appropriate.
I'll just say it (even though it has already been explored a bit in an earlier thread):
If you're trading NX for items or vice-versa without scamming/hacking/cheating, and Nexon bans you, that's completely unreasonable of them regardless of what their rules say. I think it is 10 times easier to gift someone a few packages of cubes totaling 100k nx, for instance, than to come up with 5B+ (going by the 1:50 conversion rate). Nexon isn't losing money when people do this because people who sell/trade NX will keep buying it from stores/credit. It loses money when people buy/sell items with real money (and I bet that most of those transactions include items gained illegitimately).
So if Nexon were to ban someone for the sole purpose of trading NX they've purchased legitimately for items. Is that player likely to purchase more NX if they are banned permanently? Nope. That's where Nexon would lose more profits. The buyer may not have the means to buy NX themselves anyway.
Furthermore, let's consider the following scenarios:
Player 1 decides to gift a 2x card for 2 hours of HS (it happens more often than you think) for an upcoming 2x event to player 2. Player 2 was unaware of a 2x event until the last second so they cannot run to the store to buy a card and have no credit card. That right there is trading items or service for nx. If, by the TOS, that's considered illegal, how can Nexon distinguish that from simply gifting someone a 2x card if you're just doing it as a favor for a friend? Would a ban for this be reasonable? No it wouldn't. How about a ban for a cube package with similar circumstances? Where would the line be drawn? So you gift someone a cube package for their birthday and they still want to pay you back in some way. Them paying you back makes the whole transaction a bannable offense yet them not paying you back does not? ./boatload of rhetorical questions.
Regardless of the dictatorship Nexon has over its accounts/players, the question here is a moral one, not a legal one: Is it right or wrong to ban players for honestly and legitimately b/s NX?