Because as previously stated Jetstar stuffed up! They should have allowed him to keep his wheelchair to the gate just like ALL other airlines.
Seems some people are too easily fooled by a media beatup!
I don't know the full story, but from what I saw of the PAX making a fool of himself in the interview and what I did glean from the news (not from the media beatup) the airline did not do anything wrong, however the PAX took exception to not being allowed to have his own way, and use his own "special design" wheelchair.
He's probably used to getting everything he wants due to his condition, and when he was set straight, he had a tantrum.
Media having a slow day, think "airline vs cripple" = good headlines.