What a fricken thread! Poking about the TOS and uncertain if was mentioned buuuuut;

"Warning" is a penalty issued for minor violations for which a more severe penalty than a Caution is required. As with a Caution, depending on the nature of the violation, an instruction for improvement may be given with regard to the violation. Please follow any instructions to prevent further account actions in the future.
These lines both seem rather important and imply that the GM team should endeavor to offer information to the offender when possible. It does not appear that they do this ever? Perhaps this is new addition to TOS and GM team is unfamiliar still? For something as ambiguous as "grief tactics" it would appear the GM team should be offering that advice as mentioned above. Or are taking the may part too to mean never ever never.

Further within the TOS;
If a Game Master (GM) gives an instruction based on the User Agreement and/or other rules, failure to follow the instruction is a violation and a penalty will be issued. If you are given an instruction by a GM, please follow this immediately.
It does appear that a GM is allowed to inform players of what in TOS they violated and in some ways are encouraged to do so. Why else would these clauses be within TOS otherwise?

Searching grief tactics yielded nothing so am assuming this is in reference to "Obstruction of play".

If I were a guessing Lala would say it is likely this; Aiding the enemy / Uncooperative behavior / Lethargic behavior
Or; Intentional leaving or disconnection

Both seem to imply Square searches for pattern of behavior before actioning the account if this assists at'all. Any stating that a GM will never or should never inform a player of what they had done wrong are false based upon the TOS as it is written.

Best of the luck! Would like to know outcome myself because for past two weeks we have been having intermittent issues remaining connected only when within dungeons. If friends or me are reported for this then warned I would be most displeased if could never appeal. Everything is stable in overworld when doing story stuffs, lag only occurs within duties and is completely fricken random. Trace routes confirm issue is with NTT Sacramento nodes so nothing we can fix.