I can only speak for my experience with FBA and KCBS.
Both allow pre-trimming without pre-seasoning as discussed above.
However, I have been challenged to provide proof of USDA inspection for poultry that I had pre-trimmed and vacu-sucked.
At the same event, I had ribs that had been pre-trimmed and vacu-sucked in exactly the same way.
But the ribs were not questioned.
I spoke to the REP---They believed that Poultry can be grown and processed easily outside of the USDA system. Having been a FFA kid growing up, that is true.
They said it was "unlikely" that butts, brisket, and ribs were produced out side of the USDA inspection system.
So, they were requiring proof on the poultry entries if they were not in the original packaging.
Here is what they recommended---
Keep the purchase record and actual label for the meat and have it ready for the inspector.
Yeah, I know I could raise or buy "non-USDA" poultry and just buy a bit of inspected stuff and keep the record to comply.
All I am suggesting is ---"keep the records" and avoid any hassle. :-D
TIM