The convenience store stood before the scene started and I didn't get construction out of it. It looked like they were raiding, possibly damaging the store.
My best guess would be the bomb interacted with it moreso than created.
Thinking back on the Secret Lives, I don't think there were any instances where anyone saw a Lodge spirit outside the portal predating the bomb. There had been people stumbling into it and getting ejected, but - as far as I recall - nobody seeing the entities aside from inside the Lodges. But after, there seem to be a bunch of interacts from the outside.
Perhaps it created a passage from their side rather than strictly from our side?
Also, to clarify, I should correct my previous response. I don't know if they had any express implications the Woodsman existed before the bomb, that was bad wording on my end. I meant the Woodsman didn't seem like it was being created by the bomb, so if he wasn't you could infer he already existed.