I have the free version at this moment and the secondary menu is available as an option. So if you can use it in the free version (which I can) then at least make it work right or do not call your theme “responsive”. Maybe the secondary menu should not work but it does (above 800 px.)
I test themes out in the free version before buying them for me or my clients. I understand the need to reduce features, but what remains in the free version should be supported and work correctly.