Subcontracting Plan for a Commercial Item Subcontract

My company is negotiating a subcontract to provide a commercial item in support of our client's prime contract. Our client is asking us for a Small Business Subcontracting Plan, which they say is required as part of their prime contract. Are there any circumstances in which a subcontractor providing a commercial item should be required to submit a Small Business Subcontracting Plan? 52.219-9 includes the following exclusion:

(j) Subcontracting plans are not required from subcontractors when the prime contract contains the clause at

52.212-5, Contract Terms and Conditions Required to Implement Statutes or Executive Orders—Commercial Items, or when the subcontractor provides a commercial item subject to the clause at 52.244-6, Subcontracts for Commercial Items, under a prime contract.

It seems to me that a prime contract should always contain the clause at 52.212-5 or 52.244-6, so wouldn't subcontracts for commercial items always be excluded from the requirements of 52.219-9? Am I missing something, or is the prime contractor asking for something they do not really need under the terms of their contract?