That's what it means, but you can't be a person who "mastered realistic mode" for the perfectionist mode if you didn't play through the realistic difficulty first.
What a hype killer after being sold on that mode to, now I'm going to sit back and wait till it's confirmed or what people say when the game releases.
I am pretty sure the perfectionist difficulty is available from the get go. Every Tom Clancy game lets you go for the hardest mode from the offset.