Is there a way to skip passing the "originating" flag along to SpamAssassin?

[Tom Johnson]

I have a set of users where I'd like to treat them as originating for their outbound mail (for DKIM signing, and penpals for instance), but I don't want to pass the originating flag along to SpamAssassin. 

If originating is set in SA, then headers are trusted, and RBL checks are skipped, and I need them to run for these users.

I have these users going into a policy bank, where "originating" is set.  But is there a way to keep that from being passed to SA?  Could it be unset in some hook, and then reset in another, allowing all the benefits of originating mail except in SA?  

Or could I suggest adding another option (that could be set in a policy bank) to decide whether or not originating is passed to SA?

Thanks-

Tom