You’re right it’s probably moot both in the fact that young players like that aren’t traded often and that neither Nemec or Nieghbors is likely going anywhere.
However, in the interest of discussion the best I can think of is Derbincat who got a 1st (7th overall), a 2nd, and 3rd which is pretty comparable (if not more) to the Jirieck trade return. I think we can both agree Neighbors isn’t on the same level as Derbincat was then? Or even at his two year mark? Neighbors doesn’t drive the play on the third line when he is down there. Even with his net front scoring and physicality/shot blocking, he is a complimentary player since he can’t drive the offense on his own in comparison to someone like Derbincat . The best that can be said is he has a few more years of team control than Derbincat did when he was traded from the Hawks.
To your final point, a number 1 RHD is the hardest spot to fill in the league perhaps only short of a generational/elite center. Wingers even with Neighbors intangibles and one 27 goal season (Maybe two here this year) are a dime a dozen in comparison. It might be a gamble but if New Jersey is game then you take it. The fan base will come around eventually just like with Pronger.
I have no doubt that Jake has good value. Exactly how much I don’t know…perhaps someone better than I will find a comp. A passing thought, perhaps it doesn’t have bearing since it was so long ago, but Perron and Oshie were both traded for less value than the return you’re suggesting Neighbors has.