By default pega calls GetRuleSetDetails activity to identify the list of ruleset which it need to display
This activity calls GetAppRuleSets activity - At Step 6 of this activity checks if the ruleset is visible from the class by using below mentioned API. Which would eliminate any rulesets which are not visible. I am not sure how this API determines it.
boolean isClassVisible(java.lang.String aClassName)
Indicates whether a particular class is visible to the rule being edited (according to the list of rulesets).
aClassName - the name of the class
true iff the class is visible