Joseph, regarding closely held corporations you are almost certainly right. It does seem anomalous to allow Jews to exempt themselves from prohibitions just by declaring themselves a corporation. However, if it is a public corporation whose present shareholders are all Jewish but might not be in the near future it gets sticky. What about a huge corporation whose CEO is Jewish (as was DuPont when Irving S. Shapiro headed it)? It would seem that he is no different than any Jew who works for a gentile.
Gavra, Hobby Lobby is a closely held corporation and this was he basis of SCOTUS’ decision.