In plain English
FAR 52.247-7, Freight Excluded, is a contract clause prescribed at FAR 47.207-3(d)(2), most recently dated Apr 1984. The complete official text is reproduced below, verbatim, from GSA's published FAR source files.
Its text contains no sentence requiring insertion into subcontracts; see the flowdown section below for what that does and does not mean.
Does it flow down to subcontracts?
No flowdown mandate found in the clause text
We scanned the full clause text and found no sentence directing the contractor to insert this clause into subcontracts. That is a statement about the text, not legal advice: a prime contractor may still flow terms down contractually, an agency supplement (DFARS, VAAR, …) may add requirements, and clauses listed below (if any) may order this clause into subcontracts from the outside.
Where it's prescribed
As prescribed in 47.207-3(d)(2), insert a clause substantially as follows in solicitations and contracts for transportation or for transportation-related services when any commodities or types of shipments have been identified for exclusion:
Prescribing reference: FAR 47.207-3(d)(2).
The official text, verbatim
As prescribed in 47.207-3(d)(2), insert a clause substantially as follows in solicitations and contracts for transportation or for transportation-related services when any commodities or types of shipments have been identified for exclusion:
Freight Excluded (Apr 1984)
Excluded from the scope of this contract are shipments that can be more advantageously or economically moved via parcel post or small package carrier; shipments of unusual value, explosives and other dangerous articles, household goods, commodities in bulk, commodities injurious or contaminating to other freight; and shipments that the Government may elect to move in Government vehicles.
(End of clause)