Menachos 6a - Treifa passul for a korban

After a long discussion as to why we require a special pasuk to invalidate a treifa for a korban, the gemara concludes that there are actually three pesukim that come for this purpose. First, the pasuk of משקה ישראל teaches that only something which is mutar to eat can be brought as a korban, but the limitation of this drasha is to something similar to orla and kilei hakerem that never had a moment when they were permitted. The second pasuk is the pasuk of ma'aser b'eheima מכל אשר יעבר תחת השבט which excludes treifa that doesn't have enough life to pass, but the limitation of this pasuk is that it would only exclude a treifa that was a treifa prior to becoming hekdesh. Therefore we require a third pasuk of מן הבקר to exclude even a treifa that became a treifa after it was already hekdesh.

The Netziv in Meromei Sadeh uses this gemara to explain a Rambam. The Rambam (Issurei Mizbeiach 5:9) writes that produce which has not been tithed is unfit for the wine pouring because it is a מצוה הבאה בעבירה. The difficulty is that the gemara in pesachim 48a explicitly excludes this from the pasuk of משקה ישראל from which we darshen מן המותר לישראל that it has to be fit to eat. Why does the Rambam need to invalidate it using the concept of מצוה הבאה בעבירה?

The Netziv explains that from our gemara we learn that although the drasha of ממשקה ישראל - מן המותר לישראל is a real drasha m'doryasa, it only applies to things similar to orlah and kilei hakerem that never had and never will be mutar. We can't exclude from this pasuk anything that had a sha'as ha'kosher (was mutar) or anything that will have a sha'as hakosher (will be mutar after tithing). Therefore, the gemara in pesachim that uses this pasuk to exclude tevel must only be an esmachta, not a real drasha. That is why the Rambam has to use the concept of mitzvah haba'ah b'averia to exclude tevel, rather than using the pasuk of משקה ישראל.