Yzerman didn't sign the players he did, with the hope that we stay the same, it was to try and start pushing towards a playoff spot. Let's say Simon made the Wings, and starts with lets say 11 GP and being -7 for example, and he is behind the pace against the now regular season rosters. That can kill a kids confidence and then they will be told to play safe and that can neuter a more offensive minded blueliner. Happened to Smith and Kindl. When they started they took some chances offensively and then made mistakes like any young defender does, and then fall in the doghouse of the coach and are told to play better in their own end of the ice, and their confidence to take chances disappears, and they just become run of the mill players.
Conversely, he starts in the AHL as it looks like he will, he either plays so well down there and forces his way up to Detroit or more realistically he plays decently but learns to play the NA tighter checking game with lots of minutes in all situations and has a learning rookie season, whether he sees time in the NHL or not. NA is much tighter checking with less space and time to make plays, and there is nothing that will hurt him to learn at a lower level.
There isn't one single player that played AHL or any development league games for TOO LONG that were now a ruined player. That is internet BS!