I had no luggage. I asked that, as there was a clear likelihood that there was going to be a considerable delay, whether I could be placed on that flight. I was told because I had a non flexible ticket, this couldn't be done. I asked about capacity, and was told there was capacity on the delayed 1710, but there was nothing that could be done. Clearly there was something that could be done, but it was chosen not to.
You may well have received customer service that was not up to quality, however enforcement of ticketing rules is absolutely correct, even if so abysmally explained to you on the day. If however your arrival had been earlier, so that you were not checking in 25 minutes prior to the delayed departure time of that flight, something might have been achievable.
Furthermore, with security delays as they are, to expect to check in at 1845 for a delayed departure at 1910, while the remaining passengers on that flight are already screened and at the gate ready to go, while you are pre-screening and possibly a distance from the gate (especially if remote stand) is somewhat unrealistic.