I imagine the rule is that "you have to sign within x years of drafting" but stipulating "if prospect is in college, that year doesn't count [up to x times]" as well as another rule for Europe. In that case, he wouldn't need to be signed this offseason. However, that's all conjecture, he could easily be in the Kuemper boat from last year.
I can't see it possibly being an issue though. He's not likely to see any benefit from re-entering the draft. Kuemper could have been a concern because he was coming off a record breaking season and is a prospect for a team with a glut of depth in net. Another team could have selected him in the draft and put him higher on their depth chart. Coyle's not going to see any benefits like that. Signing with the Wild has him in Houston next season with current linemate Phillips, gives him a long-shot chance at the team out of training camp, and puts him pretty high on the list for injury callups assuming he doesn't make the team outright. Houston's one of the more desirable AHL teams at this point as well. Fletcher obviously wants to get him locked up and settled, so I can't see any chance there'd be a problem with him.
Remind me again why Phillips will qualify for the AHL next year. Isn't he a year behind Coyle and Bulmer? Is it his birthday?
The rule is age 20 by January 1st in season while the draft age is age 18 by some other date (October 1 maybe?). Phillips is a late '92, not quite old enough to be drafted in 2010, but old enough to play in Houston next season.