They should make their decision about Karabacek based on his own merits, not those of some abstract player.
If you're going to do this, someone needs to be willing to give up something for a guy who's going to re-enter the draft and be available with a mid-to-late pick. There is not exactly a lot of history of teams trading for guys who can re-enter the draft.
And is drafting a player in the 2nd round, signing him and having him sit in the ECHL for three years any less of a black spot? The player's still as much of a bust either way. That 2nd round pick is a sunk cost. It's used up regardless. Don't compound the issue by signing a player you don't see as having any future just to save face about not having an unsigned 2nd rounder.
For the record, I don't have any particular opinion one way or another about whether they should sign Karabacek. I don't watch him play. If they do sign him, though, it had certainly better be because they think he can contribute at the NHL or even just AHL level and not because "why not?" or because he was a 2nd rounder.