About the only two things I know for sure about this James Campbell is that he must have been considered an adult in 1760, so I would assume he must have been born before 1739 [likely a decade or more earlier] and that he must have been resident in the county of Bedford in 1760 [else the extant record would have identified him more fully as to residence].
The following discusses a hypothesis, and ONLY a hypothesis.
At the time of the binding of the two boys to James Campbell, the term "orphans" as used in the courts meant only that the father was dead - the mother could have been alive. I have reason to believe the two boys were between 5 and 11 years old in 1760. This could mean their mother was born as late as 1733. Their deceased father had been nearly insolvent, but their paternal family had been prominent in northern Virginia society and politic. Also, they had more affluent relatives in the Rust family of Bedford/Campbell County. Their step-grandfather George Rust had migrated down from northern Virginia before 1750, as had their half-uncle Jeremiah Rust [who donated the land for what became Rustville, county seat of Campbell County]. The Rust family is shown by records of the 1750s to 1800 to have owned land in what became Campbell County, near Green and Molley's [also known as Briery] creeks, near the Falling River.
Unless James Campbell was a tradesman of some sort, he seems an unexpected choice for binding out the two Hooper boys. Their half-uncle Jeremiah Rust, or uncles-by-marriage Samuel Martin and Daniel Hammack [sons-in-law of George Rust] would seem more likely choices if they were to learn to be farmers.
--> Another possibility, the one I am really pondering, is that James Campbell married the widow Hooper very soon after the death of her first husband. In this way, James Campbell might have become step-father to the boys. Binding them out to James Campbell could insure that costs for feeding and clothing the boys until they were grown would be charged to any residual Hooper estate or to any inheritance from their paternal grandmother, rather than to James Campbell or any of his lineal heirs.
There are many records involving the name James Campbell in the Bedford/Campbell area and I have not yet teased out the ages and acquaintances involved in each instance where the name appears. I do know there was a James Campbell in Bedford/Campbell who might have had associations with, or might have been neighbors to, the Rust family and their in-laws.
1) Bedford County Virginia Deeds, Deed Book 6 Pg. 42: 25 May 1778 Between James Campbell of Bedford & Robert Martin Jr. 40 shillings for 25 acres on the east side of Falling River. [I believe Robert Martin, Jr. to be the brother of the Samuel Martin who was son-in-law to George Rust.] 2) Bedford County Will Book 2, pages 384-385 Archibald and James Campbell witnessed the will of John Beard, a man who owned several tracts on Falling River. [circa 1780] 3) 1783 grant in Bedford County to James Campbell- 294 acres on both sides of Green Creek and Meadow Creek the main Fork of Molley's Creek
Possibly pertinent is a grant made in 1761 for a large tract in Bedford County, to Elizabeth Campbell: 404 acres on both sides of North Fork of Falling River. It would be unusual for a currently married woman to receive such a patent. I have seen a case in Frederick County of a January 1762 grant to a woman who had been a widow [and thus a femme sole] when the warrant and survey paperwork were submitted, who then received the grant in her name even after she had remarried [because the authorities had not yet received word of the remarriage]. Awareness of that example combined with the custom of the time makes me think this Elizabeth Campbell might have been a spinster [that is, born a Campbell], or still a widow [last husband was a Campbell who was now deceased] or perhaps a widow who had remarried. IF that final case is the actual explanation, then this Elizabeth perhaps could have been Mrs. Elizabeth _____ (Hooper) Campbell, mother of the Hooper orphan boys, and by midsummer of 1760, wife of James Campbell. This would mean that children of James Campbell who were born 1760 and later would have been half-siblings of the Hooper children. The woman Elizabeth would have been born about 1733 at the latest, suggesting that by 1775 she would have become less fertile and certainly would not have had more offspring after 1783. I don't know whether there is a James and Elizabeth Campbell family of Bedford/Campbell who match this hypothetical couple. Remember, this is just a hypothesis, without further evidence. But that's the idea I am trying to test here.
If you have info that would either support or falsify the hypothesis of James Campbell marrying a widow Hooper, such data would be a big help.