At this point, the Oilers have few reasons to not call up Lavoie. He was one of the very last cuts during preseason as he impressed the coaching staff. Since he has already cleared waivers, he will not have to clear them again if the Oilers want to send him down. That is unless he sticks with the team long enough for his grace period status to expire.
Similarly, Lavoie is on an entry-level contract. The Oilers can actually afford to call him up. Something not all team can say at this point with the limitations of a flat, hard-cap NHL.