I think it's important to have a standard API going forward rather than porting to ten different APIs. We'd be more than happy to support OpenRC if you implemented the logind APIs we require.
An API doesn't have a license. It is just the code which has a license. Do you mean you want to copy the code to reuse it under OpenRC, or are you really talking about the API?
Regarding API license: Just ask systemd mailing list. They will tell you that API doesn't have a license, only the code.
