I don’t understand why he wouldn’t include this experience, because it is real, regardless it was done with you and/or your wife. Why hide it? Especially since it seems that it could be a differentiator…maybe/maybe not for college admissions, but certainly for future internships and jobs.
Regarding the example of authorship on the research paper, I could easily make the case it was less than ethical to not put your son as a co-author, when you state had it been anyone else you would have put them as a co-author.
Was this an interview with alumni or admissions? If alum, I don’t know of any Ivy where the alum interview holds much, if any, influence in admissions.