Synchronize

When a delete is detected on either the source or the destination, the application will ignore and take no action.

Copy

Delete Policy Ignore Both is not applicable.
With transfer type Copy, data transfer occurs in one direction--from source to destination. so Delete Policy Ignore Both is not be applicable. The default Delete Policy for copy jobs is Ignore items deleted from the source.

Migrate

Delete Policy Ignore Both is not applicable.
With transfer type Migrate, the application does not run change/delete detection on subsequent job runs, so Delete Policy Ignore Both is not applicable. 

Publish

Delete Policy Ignore Both is not applicable.
Based on the definition of transfer type Publish, it must make deletes on the destination to ensure it matches the source, so Delete Policy Ignore Both would not be applicable.

Move

Delete Policy Ignore Both is not applicable.
Based on the definition of transfer type Move, it must evaluate the source, transfer all content to the destination, then delete everything from the source, so Delete Policy Ignore Both would not be applicable.

Copy folder structure

Delete Policy Ignore Both is not applicable.
With transfer type Copy Folder Structure, the application does not run change/delete detection on subsequent job runs, Delete Policy Ignore Both would not be applicable.