Am I the only one who has read the entire thread? Although the OP posted that he was unhappy having to show his BP, it turned out that it wasn't that request that was the problem - it was that KM had decided to do something different to what they had done in the past, and doing so without any notification or announcement. It was the change in procedure which the OP and other passengers did not know about or expect that was causing delays at the door.
There is NO PROBLEM showing Bps at the door. Nobody has said there was a problem doing this.
Yes all that, plus whilst I am more than capable of producing my boarding pass within a matter of seconds if requested the same cannot be said of most of the tourists in front of me who immediately revert into window licker mode when asked to follow a simple procedure.
P.S. I flew KM to BRU today and guess what – no BP check at the door! That's twice now since this "new procedure" came into place.