Word or phrase for 'they shouldn't care, and if they do, it doesn't matter'

Question

An example of a relevant situation:

Person A: "Should I announce x? I'm worried that y people won't (like/understand/accept) it."

Person B: "I don't think y people will mind. And if they do, they're not your (target audience/their opinion isn't relevant/it shouldn't matter to you personally)."

In this example, instead of person B saying one of the three options above, they could state something like 'Indeed, it's a foo' or 'Don't worry about it, it's a bar.'

The key idea is that the word Person B uses is:

• Reassuring and sympathetic to Person A
• Follows the logic that, by having a negative perception of Person A's action or statement, the critic is either missing the point, lacking awareness, or not the intended audience for the action or statement by Person A.

A word with similar usage would be conundrum, as in, 'Indeed, it's a conundrum', however, instead of offering no clear opinion, this word would indicate that if the negative outcome were to occur, it would not be problematic.

Answer 1

Those who mind don't matter

Is the phrase often used to reflect this meaning, taken from the quip:

Those Who Mind Don’t Matter, and Those Who Matter Don’t Mind

The quotation is frequently credited to Theodor Seuss Geisel (Dr. Seuss), however as Quote Investigator attests:

There is no substantive evidence that Theodor Seuss Geisel wrote or said this expression. Researchers have been unable to locate the statement in any of his books.

The earliest non documented use of the phrase I could find, was by Bernard M. Baruch:

Often quoted response to Igor Cassini, a popular society columnist for the New York Journal American, when asked how he handled the seating arrangements for all those who attended his dinner parties... the full response was "I never bother about that. Those who matter don't mind, and those who mind don't matter." - Wikiquote

Quote Investigator, references a journal written for municipal and county engineers printed in 1938 as the first documented use of the phrase:

Mr. Davies himself admitted that it was highly controversial and open to criticism; but criticism concerned both mind and matter. “Those who mind don’t matter, and those who matter don’t mind!”

And references the fact that the phrase is in quotation marks, so was likely in circulation some time prior to this.

For a more contemporary (and slightly altered) usage, you might check out this blog post from the blog, Art and Science of Choosing Happiness:

Remember that imperfections are perfectly normal. Those who care don’t matter and those that matter don’t care. The only comparison that might ever make sense is considering whether we are being our best selves - based on what’s important to our own happiness. Define your own happiness on your own terms and make choices appropriately - then be the best you in those chosen ways.

Answer 2

Here are three phrases. Tell me if I'm close, and perhaps I can find something better.

I don't think they'll mind, and if they do

1 it'll be like water off a duck's back

You say that criticism is like water off a duck's back or water off a duck's back to emphasize that it is not having any effect on the person being criticized.

(Collins)

2 Or vulgarly:

they know where they can stick it

If you say that someone can stick something, especially a job (or in this case, their negative opinion), or if you tell them where to stick it, you are rudely refusing it (or emphasizing that you do not want it or like it).

(Collins, italics mine)

3 if they do who the f*ck cares?

That's a rhetorical question, and it conveys that I don't care.