Here are some points which are omitted from, or wrongly stated, in the BBC article cited in the opening post above ...
* Ota Benga wasn't a "teen." He was born sometime in or around 1883, making him on the order of 20 or 21 years old at the time he first came to America. He was an adult.
* Ota Benga had been married and fathered children before first coming to America.
* His first wife and children had been killed by Belgian colonial forces while he was away from his home village. He was subsequently captured and sold into slavery.
* Verner had been contracted to find Pygmies willing to come to the USA for what was originally conceived and proposed as a grand anthropological exhibit at the 1904 event in St. Louis.
* Verner encountered Benga for the first time as a captive of slavers on his way to recruit exhibition participants from the Batwa society / group. Verner purchased Benga's freedom (or, from a more cynical perspective, Benga per se) from the slavers.
* Benga was not a Batwa, so he was the odd man out among the Pygmies Verner recruited.
* Verner brought the 5 recruits to St. Louis, where the intended anthropological exhibition seemed to have devolved into something more akin to a circus sideshow environment. There were representative members of indigenous peoples from all around the world present - e.g., a group of Native Americans including Geronimo.
* The 5 Africans had a less than grand experience in St. Louis. Even though they were not confined, they couldn't circulate around the grounds without a gaggle of visitors following them as curiosities and tacitly expecting them to be entertaining.
* Following the St. Louis exhibition Verner returned all 5 of his "specimens" to their homeland, which was part of the plan / proposal all along.
* Some accounts claim Benga remarried a Batwa woman after his return. However, she died. More generally, Benga couldn't integrate himself into the different Batwa group / society, and his own group had been decimated to the point he had no native society to which he could return. There was little or nothing for him back in the Congo, and he requested that Verner take him back to the USA when Verner next returned there.
* Verner consented to bring Benga back to America. Insofar as this was above and beyond the original recruitment "deal", Verner thereby adopted an unexpected responsibility / liability in the person of Benga.
* Returning with Benga in 1905(?), Verner found himself in financial straits and needed to travel to solicit new business / opportunities. He arranged for Benga to "crash" at the American Museum of Natural History in New York, where Verner himself was attempting to secure a position. This didn't work out well, and at the suggestion of the museum director Verner moved Benga to another negotiated residence gig at the Bronx Zoo.
* At the zoo Benga was not confined at all, but displayed a preference for hanging out in the Monkey House. As had been the case at St. Louis and the museum, he couldn't move around without attracting curious folks. This daily presence eventually became something of an exhibit in itself (cf. the museum posting a sign describing Benga himself).
* The ensuing scandal decried by clergy led to Benga's subsequent transfer to a Long Island orphanage and eventually a move to Lynchburg VA, where he spent the rest of his life. These latter events were done under the supervision of some of the clergy who'd condemned the zoo situation, by which time Verner seems to have ceased to be a significant benefactor or connection.
Anyway ... Ota Benga ended up a "stranger in a strange land", and this was at least in part the result of decisions he'd made. He wasn't a captive, and his sad status as a lone individual "exhibit" occurred during a second presence in the USA that he requested. We can only speculate whether his request to come back to the USA was wise and / or whether Verner was wise in going along with it.
Naturally, none of this justifies the tacit and overt racism exhibited by the various parties connected with the Ota Benga saga.