Hyperion *lead* project, would be more correct.
Amiga Inc “contracted”(outsourced to) Hyperion for Amiga OS 4.x development, would be more correct.
There's nothing wrong with the original statement.
This is very misleading as the board is not locked to AmigaOS4, but instead AmigaOS4 is "locked" to the board. It can run any other OS.
There is no reference in the original statement that refers to Amiga OS 4.x is the only OS for AmigaOne Hardware.