In response to Patricia Tyson's Sept. 29 letter, “Bad bicycle behavior?” riding on the sidewalk is less safe than riding on the street as cyclists on sidewalks are much less visible.
However, on some occasions it may be necessary to cross a street using a sidewalk. If I'm cycling on the right side of the road and there are too many cars to safely get across two lanes of traffic into a left-turn lane, it might be safer to stay on the right side of the street and cross the street twice as a pedestrian, and then rejoin traffic in the desired direction after crossing.
It's difficult to tell from Tyson's description if this is what she's describing.
Generally, weaving between the sidewalk and the road is unsafe and should be discouraged, but in some situations, crossing the street as a pedestrian may be a safer and less intimidating option than cutting across several lanes of fast-moving traffic.