Not that it helps the OP one jot but IMO the fault lies with him as he failed to be at the airport in sufficient time to complete the check-in process. Any attempt to seek compensation will likely be a waste of time.

Any sort of system failure could have been corrected manually.

Oh, and unless they've done something huge with the security lines at Vegas, there's no way I would cut it this fine for a flight even with access to the premium lanes.