Every choir has a few folks who're a little off the mark. And it's different people on different days. Sometimes, it's me. But that's the way live music is, it isn't perfect and it shouldn't be. Our music director has a riff about Beethoven wanting "a little schmutz in the music" and Richard Strauss complaining when the orchestra played one of his works too correctly - and Thomas Edison predicting that the Victrola would be the end of music because it creates a false ideal of a "perfect" or "definitive" performance.
I listened last night to the audio of our daughter's wedding, and on the recording you can hear occasional errors - standout voices, missed entrances, fluffed cutoffs, wrong notes etc. I missed one entrance in the Mozart "Benedictus". We are definitely not the Tallis Scholars or The Sixteen, although we aspire to that sound. :-D But at the time it sounded glorious and you can't flyspeck these things in retrospect.
As a general rule, unless a singer is outrageously loud it's not a problem, and older cracked-voice folks like Brother Eyer (a forced rhyme for "choir") are completely inaudible beyond the choir loft rail, so nobody worries about it. We have a couple of very elderly people who love singing in the choir, and it would be horribly cruel to disinvite them because they're not hurting anyone.
Even the occasional foghorn bellower (we have one) doesn't need to be tossed out of the choir - our music director asks them to sing a little quieter "for balance" and concentrates on vocal coaching.
You sing the best stuff you can without crashing and burning, and you don't obsess over minor bobbles. As our music director says, "Nobody died, and nobody lost a million dollars, so it's all good."