Read only OG group types

I'd be prepared to pay for a feature to be added as a patch to OG and would like to receive offers as to cost. All code back into the community.

You can see the issue description, and blocks of code, here:
http://drupal.org/node/203103

In essence, it will allow the Site Administrator to set particular og group types to be "read only". A read only group can only have nodes posted by group managers/admins and NOT by ordinary members. Comments will be available as usual - no change.

What this will do:

1) OG Administration:
A global option to set groups as read only, or (although I don't need this) individual og groups types would be selectable as read only.

2) Audience tab on node creation/edit - only shows groups where the user is a manager/admin.

Alternative unsuitable solutions:

og_content_type_admin is unnecessarily complex and, I'm sorry to say, in my experience reliable (there are some fatal outstanding issues with this module)
og_user_roles - this is a great module and my use case is satisfied by this module. However, it is also complex, and has some issues with the Domain module I am also using. I also don't believe this functionality needs to be tied into the node access system (and further complicating the queries).

Security issues:
This should be submitted as a patch to OG and fully maintained within the OG module and to the standard of the OG module. This means satisfying Moshe's quality control standards to get it in as a patch!