It's been a while since I've seen this discussed and I can't remember what the consensus was about the chances he'll willingly accept the inform of R/S.  I know for a while many said this was close to impossible.

I think that top 25 is real hard - top 50 requires a bunch of extra effort

I wouldn't use an inform of r/s on a top 50 player. Because you're likely to be in a battle and the inform of r/s has negative recruiting value. And you don't need to inform a recruit to r/s him. Also, if you're in a battle and then you inform of non-r/s, when you do try to r/s, he'll tell you something along the lines of "did you forget that you told me that you would specifically not redshirt me? I didn't".

Are we looking past the fact that you're even considering a top-50 player as a RS?...  or is this just a hypothetical?  Cuz hypothetically it still doesnt make a lot of sense.  Ive successfully informed good players of RS, but be prepared to spend a ton of cash.  And to echo toys, you're probably going to be in a battle so it could get expensive.  You don't NEED to inform of RS in order to RS, but if you don't there is a really good chance he wont accept.  If you do inform, he will accept for sure