Too many people are reading in to this RE Sandin. The reality is that a 20 year old LHD Sandin is competing with Dermott and Lehtonen for games. They are not going to scratch a young blossoming defender with 166GP, who happens to be one of the team's best defensive blueliners, to justify playing the new shiny toy. Scratching Dermott simultaneously makes your team worse and hampers his development. The NHL is not a development league, the AHL's start date is ambiguous, and the SHL is not accepting players on loan unless they finish out the season in Sweden. It's a weird position.
Keefe's also not going to let an unproven, undersized defender with legitimate areas for improvement (speed, strength, defending) usurp the most coveted European UFA defender who had 20+ teams courting him, after a measly 4GP. What message does that send to future free agents? Dubas will not undermine the recruitment program they've built so well just to rush a prospect. They need to play Lehtonen in as many games as possible early on to determine if he is a) an NHL regular, and b) worth re-signing in the off-season, which could impact their expansion draft decisions (e.g. might make Dermott/Holl more expendable).
The bigger cause for concern is Liljegren, who I totally agree should have been loaned to the SHL because I do not see him playing regular minutes at any point with the current depth, even though he's ready. That league might be a step back for him, but he's looking at 1+ year without games at this point. There's less for him to work on conditioning wise than Sandin, too.