I get it, but I don't think it's worth the risk.
Taking a guy and trading him 9 days later like we did with Petry is much different in the offseason then it is during the season. Does Trouba suit up while we work on trading him, does he sit out and publicly demand a trade? It's about the worst possible time for this type of distraction even if Trouba is professional about it.
Second we would almost certainly be spending our last retention spot on this hypothetical trade, meaning we can't retain at the deadline to say improve the return on a Savard trade, or to be a 3rd party broker and also get an asset. So there's an opportunity cost to think about and it's not just a free asset.
There's too much downside to acquiring him just to try and trade him.