Your own link answers the very question you asked.
All they say is "we acknowledge it uses Box2D and we'd be happy to discuss it with the creator later". There's no follow-up, which I'm curious about too since one of the questions raised was whether Rovio would consider supporting the project.
He's been credited for Box2D in many games, including a number of Angry Birds iterations. They sit nicely along all the work on Blizzard's physics technology across all their games. https://www.mobygames.com/person/221583/erin-catto/credits/
The link has an update at the bottom from the creator (Erin Catto), there wasn't ever any drama and he was credited.