its real easy to do.

make an icon at the top. make it big, bright orange.
tap it to enter pin or pattern or finger print, etc.

then a list of hidden peeps shows up, select contact, and presto.... secret threads available as normal.

option to keep unhidden for x amount of time when idle before auto hiding again to avoid nuisance of excessively repeating login steps.

cool eh? piece of cake. integrate this and you're gold 24k all day.