I don't see where the whole "lie" concept has to be in play. This may be more a Duty to investigate/duty to report deal, which depends on so many grey areas. Worse (or better), it allows for many scenarios where Tress is played by his own staff or compliance folks, or by his own players, yet he is the one having to make a call about what to do with what he then-knows.
This will likely be a 20/20 hindsight thing. I do not in any way see it being a Tress flat out lied about something. And as to whether he "lied" to the NCAA, any investigative agency think you lied if you tell them something that is not the truth. Problem is, it is not too hard to tell them something untrue you think was the truth, because that is what someone told YOU.
If there is some problem in house, and it is not a Tress problem, but it IS a staff or compliance problem, they have to be careful in what they say. Just because Tress is not ultimately the bad guy does not mean that nobody on staff made a bad decision during the investigation - or did not send some info up the food chain and it resulted in Tress & Co. not being more proactive in the investigation. If Tress was not told something he should have been told, or he assigned someone to investigate and they came back that all was good, then it is STILL a problem, even if Tress was golden. And if it is still a problem, then I would expect a bunch of silence right now.
This is pure speculation of course. But that is sorta what we do sometimes and I do not mean to accuse y'all of anything by it. Mostly, I just wanted to be clear that "Tress lying" will likely be the farthest thing from what went down here.