In all fairness, OP's description of the incident is not very clear. As both a driver and a cyclist, the only situation I can imagine a car driving through a "c

In all fairness, OP's description of the incident is not very clear. As both a driver and a cyclist, the only situation I can imagine a car driving through a "cloud of cyclists" under any circumstance is an intersection with a second lane for turning left (or right, in left-hand traffic countries). In such a situation, a cyclist may want to switch lanes to the turning lane, and - of course - would have to indicate the lane change. If no such indication is given, as a car driver, I would expect the cyclist to continue onwards, especially if there are lights that are green. I would not expect the cyclist to swerve out without indication - and as a cyclist, I agree that this is a very dangerous situation for the cyclist, since not only you are swerving out into the direct path of a car, but you also get slower relative to it.