import bpy, mathutils

for area in bpy.context.window.screen.areas:
    if area.type == 'VIEW_3D':

        view_matrix = area.spaces.active.region_3d.view_matrix
        print(f"CURRENT MATRIX:\n{view_matrix}")

        flipped_view_matrix = view_matrix.copy()
        flipped_view_matrix[2][0] *= -1  # Flip scale-X? visibly not...

        print(f"NEW MATRIX:\n{flipped_view_matrix}")

        # Apply the new view matrix
        area.spaces.active.region_3d.view_matrix = flipped_view_matrix
        area.tag_redraw()