The "slows to a reasonable speed" exemption is significant here. Bike lanes aren't actually enough to bicyclists from getting hit, particularly by large vehicles (buses, widened pickups, etc) that crowd the bike lane. Given a narrow road and bike lane, it's awfully nice for cyclists to have people slow down as they pass.

That said, all of this is going to depend on sensible application, and I'm glad to see there won't be a strict-enforcement campaign. It goes on already-massive list of traffic laws that most drivers break every day - it's hardly surprising to see a traffic law that's impractical and dangerous to follow in all cases. Used well, these laws are about giving cops options when people take dangerous actions. Used strictly or vindictively, they make driving an impossible task.