4
I haven’t looked at the feat before but I would say no, because:
“When the item is in staff form, you can Cast the Spells from the staff and benefit from any other abilities the staff grants.”
The fact that they called out “when in staff form” you can use “any other abilities” implies that you can’t use them when it’s not in staff form.
I don’t think it’d be game-breaking to allow the passives in any form but it doesn’t seem to be RAW.