The captain should have had a quiet word with the crew, and the crew should have had a quiet word with the passengers. "Excuse me sir, would you mind if we moved you and your family to row 21, theres been a problem with the check in system.
No! You don't ever lie to passengers.
Final 3 Greens: you seem to be rolling together two separate issues here: customer service / the "right to know" and a pilot's professional duty to his passengers.
A doctor is not obliged to explain to his patient why he has decided on a particular diagnosis. That is what the doctor is paid to do. A solicitor is not obliged to explain to his client the legal reasons behind every decision he makes. He may choose to do so, but he is paid for his professional judgement. Likewise, a professional pilot is not obliged to tell his passengers why he has decided the aircraft is safe to fly (or to provide details on fuel or any of the other examples Bealzebub gave). He is paid to exercise his professional judgement and that, ultimately, is all that counts.
That is
not to say that non-communication or over-communication (in any of the above situations) is either acceptable or desirable. I think you need to get this into perspective. It seems you know a little too much about one issue. A little knowledge can be a dangerous thing...
Bealzebub: thank you for your informed comment.