The arrestee is not the manager of rapper Tekashi69, but another member of his crew, Fuguan Lovick, according to TMZ, who is booked for first-degree reckless endangerment.
The question hanging out there: how did a gun get inside a building that presumably puts visitors through metal detectors? Do celebrity(-adjacent) guests get a bye?
By the way, TMZ reported that Tekashi69 was dropped from the Soulfrito concert planned next month. Indeed, the Barclays Center website no longer includes him in the text of the listing, but he's still on the poster.