You quoted only half the sentence that Viva wrote. You left out the part where she compared the person who sings off-key with someone who sings well but is not in a state of grace.
I left it off, because her comment was stupid.
God is more pleased at a dog than a person who is in mortal sin. Should we invite all kinds of animals into church because of this false comparison? Certainly not.
She also said that she's been in many choirs and seen things. I've been in choirs too and seen things too....those in the choir who are not living an honest Catholic life.....far from it.
Who cares? Their job is to sing. As long as their situation is not openly scandalous, their state of soul is none of your business.
If you and Viva were focused on singing properly in the choir, and also attending mass, you wouldn't have time to "see things" or to critique others.
But maybe all that matters is that they sing well, so as not to offend those around them.
Yes, their job is to sing well. End of story.