Having Copp for one year at a manageable cap hit, and losing him as a UFA isn't a terrible outcome for a team that is trying to contend. If he really enjoys the season, maybe he can be re-signed by the Jets as a UFA after next season. But if that happens, I think it will be through a negotiated 1-year contract, not through another grinding arbitration process.
I think it all depends on the trade market. If the Jets can only get a low value draft pick for Copp, then it's worth it to keep him for next year. If he can return a couple of 2nd round picks, or so, then maybe it makes sense to trade him now.
But it's pretty clear that the Jets are in "win now" mode, so if they think Copp can help them win this season, they might be willing to sign him for one season at a lower AAV, and risk having him walk next season.
Just for information - on a 1-year deal, Evolving Hockey projects Copp at around $3.7M. On a two-year deal, Copp is pegged at around $4M. If the Jets could get him on a deal in that range, I think that might be preferable to a trade, unless the trade market for him is really strong.