Thanks for the reply.  I have reviewed Publication 598, Tax on Unrelated Business Income of Exempt Organizations. 

Publication 598 (Rev. March 2021) (irs.gov)

Within that publication is information on the exclusions I site above.  That is kind of what the organization is hanging it's hat on.  For some reason, their CPA seems to ignore the exclusions and continues to feel tax is owed...but does not provide a sound reason as to why.  I advised them, at a minimum, their CPA should provide substantiation for the position he is taking.  He very well could be correct, but he has to provide his basis as to why he is taking that stance.  He also should provide his reasoning as to why the exclusions do not apply.