It actually is. But you need another "middle man". And that is a common Amiga RGB to SCART cable. Plug the SCART end into this gizmo and you get a component output.
I know you would prefer a direct Amiga RGB to component output. So would I. But it seems that this is our only choice.
Are you (or anyone watching this) registered at that German forum64.de ? They have schematics attached in one of the posts. But I can't get to them.