It is down to the crew on the day. What clearly didn't happen was proper communication between the person who booked the ticket and EasyJet. As EJ don't know the passenger, it falls on the booker to start the communication. For me I want the person flying to accept that in an emergency thy may not be able to get off. I'll give the a personal and very invidudual briefing, but I'll make no promises. I also do this for every blind passenger I fly. (I'll also give then a tour of the outside if possible; they haven't clue what the engine is like or what shape things are). But as I am responsible for for those on the flight, I do things as I see fit, as did this crew and for that they are to be commended.
But the problem of doing your job properly is that you will get criticism. A lady who was "horizontally tall" insisted she sat on a row by an emergency exit. But there was no way she was going to get through the hatch unless she fasted for a few years. She was not happy being told that she was not going to sit anywhere near any emergency exit. I discriminated against her because of her size she said. I totally agree. I did. I'd prefer not to, but I had no other options available.