Hi,
The bug about redirecting to access denied is fixed in the latest source code but is not related to the UserCanOnlyEditModuleAsDraft function, it correctly returns false there because it is not true that Admins or Content Admins can "only" edit as draft, they can edit anything at all and are not limited by draft settings.
You can either get the latest code or as a workaround add the content to a private page protected by roles and edit from there where you will have the context of the page edit permissions available.
Hope it helps,
Joe