No, the characters are not rigged. In the reddit that YOU posted it explains that the gear you get is set for your play style. Which I disagree with, but that's besides the point. The reddit says nothing about certain characters never getting anything. If you never get anything, you're just unlucky. A PLS (Personal Loot System) can operate using a "Random" Number Generator (RNG). The loot will still be personal, meaning only you can see it and take it.