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",
Doesn't work for Ryanair though as seats are not allocated at check in.
That's why FR block rows depending on the passenger load.
As a late comer to the discussion, when does your proposed " Little white lie " become disinformation?
There is a balance to be considered as all too often I read complaints here about mis-information and lack of information.