Disagree, that's where it'd be needed the most. Small stations are the least defensible, especially where it's company's only station because of low membership. That's also why I like scalable siege mechanics where cost of entry is low to moderate but the cost of combat scales proportionately to the participants. For instance the Sanction Vouchers idea, perfectly scalable when it afflicts all of an invader's stations with the debuff and/or all of its sieges with higher declaration costs.
But I digress, this is a warp thread not a siege thread.
Ostensibly, as far as I understand it, the station core anchors the station, preventing movement physics, and raises the safezone, preventing damage and weapon physics- that's two separate mechanical effects caused by the same object/system. There's no reason at all that anchoring and the safezone should be bound up in a rules sense even though they share the same origin. If they were bound up mechanically, dropping a safezone would remove the anchor. Though removing a station's anchor would drop the SZ because you're disabling the core, so I guess being anchored is sort of a precondition to putting up an SZ.