PSA: GMs are banning players for attendance.

the logic behind it is that the person who bought the nx is a lost customer for an actual cash sale.

they want people to buy nx with money, not mesos.

Yes but the person who bought the NX to buy the mesos is still a paying customer. Realistically, it's probably more of a legal issue than anything. People who buy NX don't normally buy it once and people buying NX to buy mesos will almost certainly buy again. From a business standpoint, if they're not completely braindead then they know that buying NX for mesos is GOOD for business, not bad.