I wouldnt risk it personally but I can see how it could avoid a ban, if it's a less popular game. you could share a legit cart with 20 friends and nintendo would see 20 different consoles using that same game, and you dont get banned for just sharing games. but they could still see in the logs that the cartridge was inserted and played during a specific time period, and could see that more than one console has been playing that "cartridge" during the same time period, even if everyone involved had only been playing it while offline
and since it's not possible to change the actual internal clock value, you can only change the offset, it's difficult to spoof that. unless the logs just go by system time and don't track the actual rtc value (plausible, because you could just set up a console without setting up a connection, and never enable internet time sync. therefore the internal clock value can not be relied upon and they have to use user-specified system time)
in which case they might not go by the time at which a cartridge was inserted and played, because two consoles with the wrong time could show the same date and time in the logs, when in reality the cartridge was only used in one console at a time. you wouldnt have to worry about that then. but if they see that 2000 consoles have registered and played a specific game in the same week though then it becomes more obvious that it's a pirated copy (it's physically impossible to pass around a legit cartridge between 2000 users in a short enough time frame lol)