THIS right here:

[Hortensis]

10. 5. Should we make officials sell off all ownership

and resign from all positions in commercial ventures before taking office, lest someone try to curry favor by doing business with those companies?

Since businesses bring profits to their owners, ownership of a business would mean much more danger of corruption than owning a non-profit charity from which the candidate takes no more than a salary (or in this case not even that).