We aren't. If we dealt Steen and signed Maroon, it would be because others on the roster have taken over Steen's role. If that were to happen, it would be because we need more of what Maroon brings. The benefit of adding Maroon is independent of the benefit of keeping or dealing Steen.
I would not argue who has more talent between Steen and Maroon. They are very different players, who bring very different things to the table.
I'm not slamming Steen. He's a fantastic two way forward who, as others have noted, does a lot of little things very well. I particularly appreciate his mastery of the reverse hit. But Steen is redundant on this roster. And he's (arguably) on the decline. His performance has decreased in inverse proportion to his ice time. And he's (allegedly) got a personal beef with the captain, and (supposedly) an attitude issue.
I can't knock him for not getting along with Pietrangelo--because I'm not the biggest fan either. But the negative attitude has been apparent in his body language over the last couple seasons--which is the biggest reason I think he'd be open to being dealt, as long as it was to the right team.
Personally, whether we sign Maroon or not, I think Steen needs to go. Even if it were the case that management wanted to "replace" Steen with Maroon, I'm not so sure that it's a "downgrade". I think their offensive output will be comparable this season. For all that Maroon is knocked for being slow, Steen isn't that fast a skater, either. And while it's not universally agreed upon that adding a big body to the lineup will help solve our PP woes, it certainly can't hurt.