Shakespeare had a character say, "First we kill all the lawyers."  Today the line might be, "First we cancel all the seminars."  I wonder if the CPA pontificating at the one your client attended, was from out of state?  What I usually come across when researching questions like this is that "it depends" -- on whether state registration laws allows corporations or LLC's to be licensed to sell things like insurance, or securities, or real estate. 

Ask your client why the commissions weren't paid directly to his company.  Is the answer, "that's illegal" ? Then he's out of luck if IRS challenges the "assignment of income."  On the other hand, if he answers like Fleischer in that Tax Court case, "it would cost millions to do the paperwork," then IRS would tell him they doubt it but he should have done it anyway.  

The Fleischer case doesn't set any new precedent, and your "facts and circumstances" might be different, or at least you could try to distinguish them.  What's interesting is that you can't find it on the Tax Court website, because it's "sealed."  Obviously you can find the opinion online from other sources.  The Tax Court recently has had this problem of sealing an entire case when there may be just one document that needs to be kept confidential, perhaps because of an unredacted SSN.