Today's paper gives a clear answer.
Notice that there's no bike lane in the photo. Because Silverton Road has inadequate bike facilities, it's not surprising that people will bike on the sidewalk. (And even with a bike lane, auto speed and traffic volume make bike travel on arterial roads uncomfortable for most people - Lancaster Drive and those who bike on the sidewalk there demonstrate this.)
But then Oregon law and law enforcement has a catch-22 that sometimes acts to punish people for biking on the sidewalk when there is no good alternative.
According to Ray Thomas' legal guide Pedal Power, Oregon law (ORS 814.410) defines
Unsafe operation of bicycle on sidewalk; penalty.According to the article, the person on bike "was cited for unsafe operation of a bicycle on a sidewalk." We don't know exactly what happened and speculation should not get too far out in front of the facts.
(1) A person commits the offense of unsafe operation of a bicycle on a sidewalk if the person does any of the following:
(a) Operates the bicycle so as to suddenly leave a curb or other place of safety and move into the path of a vehicle that is so close as to constitute an immediate hazard....[or]
(d) Operates the bicycle at a speed greater than an ordinary walk when approaching or entering a crosswalk, approaching or crossing a driveway or crossing a curb cut or pedestrian ramp and a motor vehicle is approaching the crosswalk, driveway, curb cut or pedestrian ramp.
But it's important to remember that in some parts of town people bike on the sidewalk because the road is a bad place to bike.
The crash also highlights uncomfortable questions about class, status, and ethnicity.
At the very least, in the absence of adequate bike facilities, it is profoundly unfair that a person on bike who is dragged 150 feet and likely injured should also be cited. The big truck has all the advantages.
In any event, until the Salem area invests in a good network of bike facilities that gives people compelling and safe alternatives to biking on the sidewalk, people will bike on the sidewalk and we will have preventable crashes like this.
Whether they are on bad roadway facilities or are forced onto the sidewalk, people on bike too often feel second-class.