Free seating is not a oneworld benefit.
The oneworld benefits are listed here: http://www.oneworld.com/ffp/oneworld-benefits

There is no requirement for a oneworld airline to provide benefits over and above those prescribed benefits that they provide to their own status customers.

A oneworld airline may provide additional benefits to their own status customers (eg AirBerlin Silver members which are oneworld Ruby), but not extend this to all oneworld Ruby members.
Some airlines do extend some benefits to both their own status customers and the equivelant oneworld tier, above the oneworld benefits.