Obviously, I do not know the details, but lights without a cut-off and/or helmet lights directed straight into the eyes of others can create as much danger as no lights, and in this case squaring the danger on others. At times the offending party are actually runners with helmet lights pointing up.
If the rider is riding on the proper side of the road, no bicycle light will interfere with his or her ability to see. My lights have a wide spread but they don't interfere with motorists coming from the other direction and those are sitting about 6 to 8 feet nearer to me than a cyclist on the other side of the street.
On the other hand, a bicyclist...not a jogger, but a
bicyclist...who is riding counterflow to traffic has no expectation of me dimming, dipping or turning off my lights. His contraflow riding was already endangering himself and me. Every state in the US has laws that
require bicyclist to ride
with traffic, not against it. I can't make accommodation to people who are breaking the law out of "courtesy".
Nor am I going to "blind" him (or her) all that much because they are already riding into the lights of cars coming at them.