I'm pretty sure it means just this year doesn't count. So basically this year counts as one of his 4 active years in ND's eyes in terms of playing 4 in 5. Again, there might be a loophole, but that seems to be the situation right now. It also doesn't effect him if he were to transfer because it seems to just be a ND rule and I think in the NCAA's eyes he would be a redshirt this year if plays 4 or fewer games. None of this probably matters anyway because if he does end up doing a fifth year then its probably because he turns out not to be good in which case he would probably transfer and be able to count the suspended year as a redshirt.
One thing that is interesting with Kelly's comments about it being week to week is that it might not be a failed test for marijuana, but an inadvertent PED use which was successfully appealed. It could be a case where he tested positive for a PED but was able to prove it was from a contaminated supplement or something else which were certified safe. If that were the case, then he would be able to practice, but not play until the PED cleared his system and he got a negative retest. Theoretically it would explain the situation from the initial 4 game report (reported as failed test and assumed it was the same 4 game as Dex), to the season long report (failed for PEDs is a year long suspension), to the subsequent uncertainty (the appeal got rid of the year long suspension but still holds him out of games for an indefinite time). However, while both this scenario and the more commonly accepted one are both speculatory, this one seems less likely given we have had a few occurrences of the commonly accepted.