I'm having the same situation in an UAT cluster configured as Active/Passive. I wanted to install SP3 last sunday and I got the same error: No passive nodes were successfully patched.
What I do found (but didn't try it yet) was a workaround. That was to go into the Cluster Admin, go to the SQL Server resource and remove all the available servers but one, so you serve the resource with only one server (no actual cluster there...). Then, perform the update on each server. Because you don't have the instance in a cluster environment, the SP3 will not try to update the passive node. Finally, go back to the resources and set everything as you have before....
I know this is not a good way, but perhaps this can help...