I agree with all of that outside of the last statement. 5 star commits at WR rarely impact the team in year 1.
If I was in his shoes, the only reason i would leave WR U in his position, would be if I landed somewhere that has a system, where passing is the priority and the defenses faced will be weaker. If not, I'd work my tail off to step into stardom role at WR U. If he expects to make it to the next level, going somewhere else is unlikely to provide a greater opportunity than the one at OSU. If you can't beat out incoming Freshman that have never played at that level, how could you possibly expect to beat out NFL talent?
I do see where you are coming from. I actually asked roughly the same question about him because my initial thought was that with the expected departures of Harrison and Egbuka he should move up to WR1, why leave?
That said, I think that we should think about the mentality of most of these guys. To their defense, it has to be a MAJOR mental adjustment to go from being THE MAN in HS and basically your entire football-playing life to getting on campus and finding out that you are not only not the greatest player the staff has ever seen, you aren't even the best at your own position on the current roster and you aren't even good enough to start or possibly even play as a freshman.
Imagine yourself in that situation. You are a WR for a HS team and you just DOMINATE the opposing DB's that try to cover you. You are THE STAR of your team. Moreover, it has ALWAYS been this way for you. You've been THAT GUY ever since you first tried on pads. Then during Fall Camp your position coach calls you into his office to tell you that they plan to redshirt you. I'm sure he would try to put it as nicely as possible but the underlying message is: "You aren't good enough to contribute to this team." I think that would be devastating for a lot of guys.
I think it makes more sense when you think about that mentality. Now you have spent years at Ohio State toiling behind Olave, JSN, Marv, Egbuka and there is no guarantee that both Marv and Egbuka will leave (probably but from Fleming's perspective he may not 100% know that) nor is there any guarantee that you'll beat out Tate and the Freshman for WR1 nor even WR2.