Truth. Bolster on live right exists in level 50 Warzones, it just doesn't do anything (since everyone is at the level it tries to bolster too). With the switch to the rating system, the bolster effect will still exist in Warzones of all levels, and now will do something if the player's gear isn't up to the task.
I may be mistaken, but I believe Bolster is always active in a warzone as it is, 1-49 and 50. This really doesn't change that at all.