I had this same thing happen in the mid 90's at a commuter. Got a letter of warning and it was expunged in two years. I started getting my interviews before the two years was up, so I put it on there. Both majors asked about it and seemed happy with my explanation of the event.

My take was that they just wanted me to take ownership of the event.

When asked "if the ground personnel were at fault, why were you even questioned about this?"

"Because I was the Captain."

End of question, got job offers from both.