This is not the first support for the Outer Spiral in terms of size or distance from either end of the Outer Spiral. It is the first support that was installed to support the Outer Spiral.
This piece fell from the sky into Reversible Guy’s hand because he needed it at that moment to add the Backboard for the Caret Splitter. To get it to fall from the sky I had to think of a reasonable explanation. There is a scene that explains it, but that scene will only be available on the DVD (or to Patreon patrons).