If it wasn't Sieloff, it could have been anybody else. What if it was Mark Stone who re-injured Clarke? What would people say? Unfortunately, damage was already done previously and MacArthur's career was destined to end up like this.
Sieloff was a 2nd round pick and used to be a decent prospect. It didn't materialize but he's almost 24 y/o now. He's been putting the time and dedication so you reward him by giving him a few NHL checks in a lost season. Nothing wrong with that. It might be his only stint in the NHL.
Chiasson for Sieloff was actually Dorion's 1st trade as a GM (2nd with moving up to get the 11th OA pick). It was a sign of things to come. Trading a NHLer (even if bottom-6 forward) for an AHLer.
To be honest, there's not many prospects to call up from the AHL right now.
Hogberg needs more time in the AHL and you only have 2 goalie spots anyway (and they're healthy right now). Driedger hasn't played much this year (he was injured a while I think) and looked not NHL material in his last NHL game.
Jaros and Perron have been injured for a while. Nick Paul seems to be injured too. Gagne is still young and has finally started figuring out pro hockey this season, he's a long term project so it's a good thing to take your time with him. Chlapik, Harpur, Chabot and McCormick are already up with the big club
White might be the only guy but I guess they want him to develop more in the AHL. No idea what's the status for Englund. I think I would have liked to see Pokka or maybe even Lajoie over Sieloff though