These are the sorts of prohibited behaviors that can be heuristically recognized by technical means (e.g. static analysis), but where any such recognition would necessarily result result in tons of false positives; and so those issues, when raised, must be passed to a team of human auditors for determination.
This is, by-and-large, why App Store submissions — even for updates — still require that human-auditor step. They're always watching for those seemingly-minor "this app got sold to someone evil" updates that slip in spyware — the kind you see often with Chrome Extensions.