OK an explanation to your question would be:
Mechanically
When a model is buried it is removed from the table and placed off table(the void). This allows it to move from the building to off the table. The model is now buried but still in play when it goes to unbury next to the death marshal it moves from off the table(the void) into the building. As the building is an enclosed build with walls, floors and a roof the model now has to pass though part of the building to get inside. As the model is being placed from off the table (the void) and into the building. Under the advance building rules it would not be able to place into the building and would have to place into deployment zone as the failsafe unbury rule.
The Thematically
The death marshal grabs the poor unsuppecting model it struggles but the death marshal over powers it and stuffs it into the pine box and nails it's shut. It bulls up the floor boards of the house digs a whole and places the pine box into it. Then he replaces the floorboards the poor model continues to struggle he manages to get out of the pine box but can't break through to the surface because of the floor to the house so he has to tunnel his way out when he finally breaks through he is located where he first came into the area far away from the others but alive.
And the paragraph below covers the full spectrum of placements (summon, unbury, flight and replace). As both summon models and the new models that replaces the old models are not in play at the start of the effect and Buried models and flight models are in play at the start of the effect.
- If a model was in play at the start of the effect, and in play at the end of the effect, the effect can't be used to enter or leave the building. Instead, if it was inside it has to remain inside, and if it was outside it has to remain outside.