Your post prompted a memory of my mother and I attending a national show. There we were in front of a amazing work ( my opinion) and my mother ( hard of hearing and in her early 80's) blurts out ... "I thinks is ugly" .... I was mortified as the creator was standing next to my mother . I lean in and tell her who is next to her... and then she says " Its still ugly". I was beyond embarrased ... and my sister and I both took about 5 steps away from her. She had never been so ..innapropriate. So I can feel for you situation , and offer to you that your gratious lack of response was problably to most appropriate response.
At that age ( I am just learning) .. you just never know what will come out of their mouths.