You're right, if the driver had to "swerve to avoid" two cyclists, the driver was not keeping an assured clear distance. Yes, the cyclist should have had a reflector (and blinkie, too), but if any driver hits someone from behind, it's the driver's fault, period (that's the law in Ohio, anyway). By law, drivers must always drive at a speed to avoid hitting what's in front of them. That's cold comfort to the deceased's family, but the driver should not be let off the hook.