This is typical procedure in every airline. The person's own wheelchair is unlikely to fit through the isles, may be impossible to store in the plane cabin, and is generally a bad idea all around.
The use of isle chairs, or wheelchairs designed for planes, for those not mobile enough to walk in the plane, is always the norm.
Honestly, this guy just seems to be overdramatic. The isle chair is only used in the actual plane: he could have taken his chair up to the plane's entry, transferred into an isle chair, and then his chair would either be stored if it was a collapsable and there was room, inside the plane, or checked in, and he would use the isle chair until the flight was over. Dragging himself around the airport was for nothing but show.