Did you discuss the subject with him?
Adm. and Madame Hillenkoetter were essentially our grandparents. Mom’s mom (my Nana) was their long-time (many decades) housekeeper, and since Mom’s dad wasn’t around, the Hillenkoetter’s helped to raise Mom alongside their daughter Jane.
His belief in the other-worldly nature of UFOs was something he expressed to family, but not directly to me.