From: Rabbi Moshe Sofer
To: Unknown recipient
The Chasam Sofer resolves the Pri Megadim's difficulty against Tosfos by distinguishing between two types of non-applicability: chelev's exclusion of non-kosher animals is verse-based and could theoretically be overridden by a gezeira shava, whereas Oso V'Es Beno's non-application to non-kosher animals is inherent to the prohibition itself and cannot be extended by any hermeneutic analogy. He also adjudicates a secondary dispute between Rabbeinu Tam and Rabbeinu Yakar regarding benefit from terumah, siding with a distinction between passive benefit and active feeding.
Source: Shu"t Chasam Sofer YD §67