[A13] Overhead Mountain Remains even when Surrounded by "No Roof Area"

[ArguedPiano]

I'm not sure if this is a bug or not, but simply an observation I have made.

I was mining out a small hill/mountain to create a kill box. I would continuously expand the "No Roof Area" because I didn't want any colonists getting crushed. But there was one spot that would not disappear. Hovering the mouse over this spot revealed it to be an "Overhead Mountain".
Now the part I found odd is that every single space around this spot had been set to a "No Roof Area". There was the rest of the mountain nearby acting as walls to support this roof. But with all the roofs around it removed it would seemingly be floating in mid air.

I created a new World/Colony with no mods to test this out. Here is what I did to replicate it:
1) Find a small hill/mountain.
2) Mine through the center of the hill to find an Overhead Mountain spot.
3) Keep mining until every Overhead Mountain spot is surrounded by at least two Thin Roof spots. (1st Picture)
4) Expand the "No Roof Area" to this entire section. (2nd Picture)

*Note: The "No Roof Area" is active in the first picture.
As you can see the Overhead Mountain would be floating in the air. There's no roof to support it. I also went one more and mined out the rest of the hill only to have the Mountain collapse (which I expected).

This was a very minor issue for me as I was trying to clear out the area so that raiders would have nothing to use for cover when attacking.

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[ArguedPiano]

I could only post one of the pictures at a time so here is the second.

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[milon]

Working as designed.  There's no way in vanilla to get rid of Overhead Mountain.