The jBPM5 engine does not translate processes into rules (and neither did Drools Flow). It uses a simple state machine to represent the current state and signal next states, etc. The section you are referring to however allows you to combine this with rules if you want. For example, if you want to use complex rule constraints (using the Drools DRL) in your exclusive gateway, we will generate the rules for you. Similarly, if you use a condition start event, we will generate a rule that will trigger your process if that condition is met.
The normal control flow however does not use rules or a rules engine, it works by having different state nodes trigger each other.
Kris