I am looking for a term (or a sentence) that would describe a figure of speech where one individual use a commonly accepted proverb (or thick concept or other) in order to disregard someone's opinion on the matter.
Obviously some things look better than others. If for example we consider two cities one commonly considered ugly, one commonly considered pretty, and ask 100 people which city they find more aesthetic we have likely to have a result very far from 50:50.
Yet, the proverb "beauty lies in the eyes of the beholder" can be used in a speech to disregard one's personal opinion about aesthetic as being too subjective and to not matter as would not represents most people's opinion.
Alice: I went to this restaurant last week. The food was sooo bad!
Bob: Well you know... There is no accounting for tastes! You may not like it but that's only your opinion.
In such circumstance it will be hard for Alice to convey her point as she would necessarily appear as being not open-minded (whether the ratatouille was burnt and the vegetable rotten or not) to the eye of her audience. How do we call (or describe in a few words) Bob's figure of speech?