I think that the viewer's takeaway is supposed to be that Michael was trying and in this case failing to be like his Dad. Vito's "I'm just a minor league olive oil importer" has become Michael's "I'm just an investor in a few hotels."

Also like Vito, Michael is allergic to letting anyone know his full business. So he uses a lot of fronts (Johnny Fontane and others) to avoid disclosure and most likely avoid taxes. This is true even when in this case, the business was entirely legal. Privacy, even when nothing would be lost by disclosure was Michael's personal and business style.

"When the snows fall and the white winds blow, the lone wolf dies but the pack survives."
Winter is Coming

Now this is the Law of the Jungle—as old and as true as the sky; And the wolf that shall keep it may prosper, but the wolf that shall break it must die.
As the creeper that girdles the tree-trunk, the Law runneth forward and back; For the strength of the Pack is the Wolf, and the strength of the Wolf is the Pack.