The purpose of fronting is context-dependent.
Some cases involve restriction, but other cases serve a different rhetorical purpose.
A predicate may be fronted to attract attention, convey good news sooner, or make the listener await the subject. In an answer to “Where is Zayd?”, starting with the location may simply be a natural way of conveying the sought information.
Accordingly, the rhetorical reason for fronting should be established from structure plus context, not by applying a single exclusivity formula without checking its conditions.