Hi, Charles;
You have to meet all regulatory requirements for SQF, however code may exceed jurisdictional requirements as long as it does not undermine the intent of enforcement.
As far as allergens and C. bot. control measures, I believe that CFR Title 9 (USDA), 50 (USDC), and 21 (USFDA) all expect a vigorous labeling program as a CCP to control these hazards. Control points generally are not given much scrutiny as these are seen as quality measures, or internal controls with arbitrary values which for the most part is not regulated unless it is a voluntary program such as CFR Title 50 USDC (eg. the much vaunted bureaucratic Seafood Inspection Program for export).
For the OP, it would seem that the CCP metal detection "direct observation" is borrowed from the USFDA seafood hazards guidance in Ch. 20
Metal Inclusion-Chapter-20.pdf
I would say that the OP methodology is erroneous per regulation, unless they can justify decision with other validated methods.
Hi Slab,
Again, thanks for the above.
I now recall that the US seafood PRP vs CCP debate has a long, long forum history , eg -
https://www.ifsqn.co...ol-to-be-a-ccp/
The 2020 fishery hazards guide well demonstrates that for FDA/seafood, labelling control is an allergen-related CCP. I assume as per Post 12 that the Scope of seafood's interpretation extends to all other FDA regulated products.
(I suppose FSMA implicitly agrees with FDA since allergen control is included within the "PC Group" [albeit Seafood excluded from FSMA]).
For USDA I haven't yet seen any specific, detailed, FDA-like elaborations regarding the former's allergen viewpoint or Scope. So as yet (for me), choice of PRP/CCP for USDA-regulated product is un-defined.(to be "continued").
As an extension of above Fishery text, I anticipate metal detector will also be a CCP if FDA-regulated and assuming a significant hazard exists.
Conclusion is that SQF requires to implement a CCP for labelling control if a FDA-regulated item.
I anticipate that Product involved is FDA-regulated.(?).
So likely to be 2 CCPs.
Re - "direct", Yes, I note this is emphasised regarding critical limit (Fishery-pg33/501) however the reason for SQF's fascination with expecting enhancement of "CPs" in their flowcharts has always eluded me. 
PS - I wonder whether a FSMA control option (Regulatorially-wise) trumps FDA/USDA if a discrepancy occurs. 