Status change field gets inactive when customizing done for change forbidden in Trade Promotion

Requirement: When status in a promotion is changed to 'Submitted for approval', need to disable all the fields except the status field...so that the user can only approve/reject and not allowing to change any other fields.

There is a nice document by Johannes Voglsam which states the customization required to achieve this.

https://archive.sap.com/documents/docs/DOC-61698

I have changed the business transaction 'Change attributes' to forbidden in the below path

Customer Relationship Management-Marketing-Marketing Planning and Campaign Management-General Settings-Define Status Profile for User Status.

After doing the changes, it is disabling all the fields including the status field which should not happen.

Not sure if any further customization required here. Looking for an advice/suggestions. Thanks!