This inflammatory text was clearly the headline that AP sent it out initially over the wire, because many news sites that grab the AP feeds reproduced it (the New York Times seems to be the exception in the list below):
As well as major news sites:
Some editor at AP must have realized that the headline was not exactly unbiased. It was changed about six hours later to this:
The change has been propagating slowly through the local news sites that grab the AP feed.
I found the thread of AP headline posts on the topic:
#1 at 5:26 AM said "US activist's parents confront bulldozer driver"
#2 said "Slain US activist's parents face Israeli killer": at 7:59 AM
#3 and #4 said the same thing as the story got updated during the morning
#5, at 11:21 AM, changed it to "Israeli driver", as did #6 at 12:16 PM.
(h/t SoccerDad, Zach, Vic)