Following on from my comment, I have found some (old) US government documents that seem to answer this question. TL;DR: salivary glands, lymph nodes, and fat are "pork byproducts" (thus not "pork") and as such must be named explicitly on the ingredients list.
The long answer: The USDA's 2005 Food Standards and Labeling Policy Book lists:
Byproducts must be individually declared by species and specific name in the ingredients
statement, e.g., Pork Liver, Beef Tripe, and Beef fat.
“(Species) tongue trimmings” may also be used to
identify salivary glands, lymph nodes, and fat from which the muscle tissue has not been removed.
(note that OP's ingredient list specifies "Cheeks", suggesting that these may indeed be "tongue trimmings". A different USDA website gives some idea of what is considered a "byproduct":
virtually all parts of the live animal that are not part of the dressed carcass.
The policy book further defines Chorizo (which OP's product is marketed as) as:
The product name “Chorizo” can be used for any type of chorizo sausage that is cooked, dry, semi-dry, cured and fresh without further product name qualification. Other requirements for various types of chorizo apply, including the sausage standard.
Finally, we can find the following text:
SAUSAGE CLASSIFICATION: [...] Cooked sausages and/or Smoked sausages: [...] Meat byproducts may be used when permitted by standard.
There are a few plot holes:
- There is no mention of byproducts in any type of sausage other than "cooked and/or smoked", so I cannot tell if they are allowed or not.
- The policy book has an entry that seems to forbid the inclusion of these ingredients, contradicting the quotes above:
Trimmings with fat from tongue is acceptable ingredient in cooked sausage products covered under section 9 CFR 319.180 of the regulations. Lymph nodes and salivary glands are not acceptable ingredients.