Maybe they want to show him what the playoff drive is like and have him learn from the experience.
He doesn't have to play 15-18 minutes a night to help the team and to help him learn. Just him seeing the intensity and stress of the playoff battle will help him. He will see what others are willing to do to win and can take that info with him to the offseason training.
And who knows, maybe, just maybe, he contributes to them making the playoffs.
If I were a betting man, I would side with Bennett contributing to the Flames right now, than just being a complete passenger and not getting involved at all, he's to good of a player, and determined at that, to let that happen. He has NHL speed and hockey sense as it stands right now, he just doesn't have the in game experience yet. He'll get that in the next few games I reckon and then they will evaluate where he is at and then go from there in regards to how much he'll play in the playoffs.
I think he'll be used similar to how Drouin was used at the beginning of the year in Tampa, mostly fourth line action, but with veteran guys who know what it takes to play in this league. He'll probably receive 11-13ish minutes per game, which is very valuable, much more so than the 16-18 he'd get in the AHL. I already know Sam would do well in an energy, third line role with the Flames because he skates so damn well and plays the game hard, so that may be the role he gets thrown into a bit and see if he sinks or swims, which he'll swim IMO. He might even receive some PP ice time to keep his confidence at a good level.
Really excited as a Leafs fan to get behind a team like the Flames because they embody everything I like about a hockey team, good skill and a hard working, blue collar approach to the game. Calgary is a team I can see giving a higher seed team in the playoffs fits because of their youthful enthusiasm and they are still a good, honest skilled team.
Good luck to you guys and your team in the final stretch and playoffs!