I am not sure why people are confused by the concept of random SSSS. The entire idea of handing it out randomly is that it happens for no reason at all. Everyone, equally, independent of TT or Redress status.
Handing out random SSSS by computer is probably a much fairer system than profiling people at the checkpoint by their name or looks.
A one-time SSSS, especially on an international US-inbound flight (where they seem to like to hand out random SSSS a lot) is probably just that, a one-time random SSSS.
Multiple consecutive SSSS is probably not random. Travel history, shared name with someone else, being on some list. Non-random SSSS is what redress is designed to fix.