Despite a locked period, users can still reject recs?

User poses this observance in ARM:

I thought the Status of Locked meant:  After work has concluded, periods may be locked, which prohibits all changes to the reconciliations. Users cannot add reconciliations to the period, changes cannot be made to reconciliations, and balances cannot be imported.

So why can a user reject a rec from a locked period?

Please advise,

Thanks.