They were called out by community members, and then either FBA or Carbonda directly commented when asked, confirming that NS had nothing to do with the design process. Not my story, others posted about it here and elsewhere.
Catalogue brands rarely employ anybody capable of doing any design or engineering work. NS may have requested a 120mm option when FBA didn't have one planned (we don't know). But that's a long way from design. FBA and similar operations are a one-stop-shop. Their focus is not on OEM work (not even sure they do it?), they're primarily an ODM.
It's not like NS are the only ones pretending they design, though. Lots claim it. Very few do it. Vitus (CRC / Wiggle brand) are a classic one.