How does this follow? Is the management effort in organising a brick laying company not count as work? Does the RND effort of a bricklaying company not count as work?
I would have used housing speculation as my example tbh.
The parent post is not saying that some forms of shareholding do not earn, but they are excluding any form of owning a bricklaying firm is definitively not earning. So any arrangement that involves owning a bricklaying firm is within scope. Sole Trader or Partnership for instance.
The house is the capital. Bricks are an intermediate good.
The point is, the bricks do not materialize out of thin air. The act of laying the bricks is not the only labor or capital involved in laying bricks.