I don't know the particulars of what the NCAA require for someone just out of high school being added into the University mid-season and getting to compete. But even if its cleared, I'm still not sure where he would even fit in their line-up other than dropping down the the 133 (Cortez out due to injury). As cool as it might be for him to walk out, I'm assuming Cael would rather keep Nick for 4 full years rather than push him out just to fill a spot for half a season. PSU has a few decent options for 133 like trying to get Gulibon back down, or putting in someone off the bench. That person may not as good as Cortez, but at least enough to keep something going for them. To me if they are not pulling Mark Halls Redshirt after Southern Scuffle then I'm not seeing them putting Nick out for just the end of the season.
Nick is likely just getting a head start on his classes, so that he will not be as overloaded with coursework during his next few season of competing for the Penn State. If Cael wants him to skip a redshirt season Nick could slip in pretty nice at 141 once Gulibon graduates. Not to mention the extra time he gets by being in the room with all the studs this year, before he officially suites up for Penn State.