A few points...
Friedman said the McGroarty camp and the Jets weren't talking to him. They are certainly talking to each other, especially if a trade is brewing.
Jets not fast-tracking McGroarty was an indication that the Jets are maybe not as high on his short-term potential as many fans.
Jets' prospect pool is full of wingers, and they need more high-end D and C prospects / young players. So, it's plausible that the Jets are not averse to trading McGroarty since he's a valuable asset, and that might be why they didn't sign him (bad PR, etc.).
Jets reportedly also have Ehlers in trade talks, so they are considering some major trades / shake-ups, and McGroarty would open up a wider set of possibilities, maybe even packaging Ehlers and McGroarty.
CBJ have McGroarty's college linemates in Fantilli and Brindley. They also have a ton of assets that would interest the Jets, including Mateychuk and maybe Sillinger.
Remember that the Canes tried to acquire Ehlers while Waddell was their GM. Could they consider an Ehlers-Laine reunion, if they can't trade Laine?