This is likely a good thing for the organization so hopefully the reports are accurate. Rynnas was a good goalie for the organization so don't discount that, but he was never really given a shot to prove himself at the NHL level. With how poorly Lehtonen performed in the NHL, it would be a mistake to go in to the season with an unproven backup. That would relegate Rynnas back to the AHL.
The problem with Rynnas returning to the AHL is the recent announcement that Philippe Desorsiers and the organization plan on him starting his pro career this season. Dallas already has two potential ECHL goalies in Henri Kiviaho and Maxime Lagace.
Campbell in no way has taken the reigns as a starter in the AHL yet, but personally, especially with Willie Desjardins, I think the coaches desire to go with a veteran superseded the teams need to develop Jack. This is your last season before Campbell requires waivers to figure out who this guy is, and Desrosiers or Kiviaho could compete for ice time behind Jack. The organization may decide Philippe would develop better as a full time starter in the ECHL rather than a backup in the AHL (unless Campbell stumbles).