Clipping triangle normal direction

Question

Trying to comprehend clipping algorithm given by

ClipTriangle(triangle, plane) {
    d0 = SignedDistance(plane, triangle.v0)
    d1 = SignedDistance(plane, triangle.v1)
    d2 = SignedDistance(plane, triangle.v2)

    if {d0, d1, d2} are all positive {
        return [triangle]
    } else if {d0, d1, d2} are all negative {
        return []
    } else if only one of {d0, d1, d2} is positive {
        let A be the vertex with a positive distance
        compute B' = Intersection(AB, plane)
        compute C' = Intersection(AC, plane)
        return [Triangle(A, B', C')]
    } else /* only one of {d0, d1, d2} is negative */ {
        let C be the vertex with a negative distance
        compute A' = Intersection(AC, plane)
        compute B' = Intersection(BC, plane)
        return [Triangle(A, B, A'), Triangle(A', B, B')]
    }
}

Let consider case when one point inside frustum. I don't understand why normal direction of new clipped triangle is kept for all cases.

I do enclose awful drawing, but it shows that when upper vertex inside frustum - normal direction is negative (Assuming left handed coordinate system)

What do I get wrong about it? I'm sure I made a mistake somewhere.

Sorry for awful plot =(