Chabot is much better than Rielly was at that age, there is no doubt about that. Rielly has a much bigger sample size of offensive production (last season + so far this season) so we can't completely judge Chabot on just this season. That's just something we'll have to wait to see how the season develops or even next season. It's not a knock against Chabot, he's just that young and hasn't played nearly as many games as Rielly. In the playoffs, Rielly has 10 points in 13 career games. Not a huge sample size, but he played as the Leafs #1D against tough Washington and Boston squads and still showed his offensive ability.
Defensively, it's not close. At least not yet. Again, it's not a knock on Chabot but he just doesn't have the experience and development as Rielly since he's still so young. Can he get there? For sure. Is he there yet? Nope.
Considering these facts, I can definitely see why people would choose Chabot over Rielly going forward. Especially because of their difference in age. However, Chabot getting twice as many votes as Rielly? The gap, if any, is no where close to that. Leafs bias aside, I take the proven player at this stage especially considering where we are in terms of cup contention. If I am Ottawa, I take Chabot going forward since he fits their rebuild timeline much, much better.