I've long been an advocate for this (underhanded) tactic. I've done it before and will do it again. Just keep in mind that the players WE will drop to 1, meaning not only will the player not improve at all during the redshirt year, but he will also lose skill points over the "summer" before his RS SR season. So basically the player will not be as good as he was during his JR season, asides from any IQ growth.
If the player still has a lot of room to grow and you have the balls for it, you could keep the player off your depth chart his SR season and apply the RS at the end of the year. His WE will drop during the season, but not to 1, and his attributes will still grow. Of course, this carries the very real risk that the game will still play your SR, meaning they will no longer be eligible for a RS. I would not do this, unless maybe the player still has some blue categories left.