Unbelievable that anyone would defend this officer's stop or probable cause. This officer used his headlights as a witting pretext to entrap motorists, to give him probable cause to stop them that he otherwise would not have, so that he could get his nose in the window in hopes of generating revenue for his department (e.g. DUI, suspended license, smell marijuana, anything that has a nice fine from which the department will profit).
Let's suppose that a cop encounters a road hazard. He nearly hits it and has to take some evasive action, either braking hard, swerving, or both, to avoid it. It is poorly illuminated so you can expect other motorists will do the same thing. So rather than REMOVE the road hazard, or try to alert drivers to it by using his lights or flares to better illuminate the road hazard, he thinks "Hey I'm betting I can use this!" So he pulls off, conceals himself and waits for a motorist to come along and brake hard, or swerve to avoid the road hazard. Gotcha! That right there is my probable cause to pull this motorist over on a pretext of a violation, run his plates, run him for warrants, stick my nose in the window, if I get lucky he is drunk and we'll get some of that DUI fine money. Driving erratically, swerving!
What is the difference between my analogy and what this officer was doing? Nothing! What this officer did is at the very least extremely unethical, but I'm betting a number of attorney generals, judges, and juries would say it rises to the level of an UNLAWFUL pretext. He had NO probable cause to stop anyone on these basis under such contrived and KNOWING circumstances. Given how obviously unethical and deceptive is his behavior, I do not have any doubt at all that this officer is ethically capable of intentionally using his high-beams in order to get these motorists to flash him, creating or manufacturing his own pretext.
Instead of taking this unsafe vehicle (which is in violation of Michigan law, BTW) back and getting a different vehicle, OR just ignoring the motorists who were flashing him, he just decides it's some kind of gift he can exploit in order to stop people that he would otherwise have NO authority to stop. A young man is dead because he rightly protested such an unlawful or dubious stop. Everything that flows from such a highly unethical and dubious, likely unlawful stop thus falls onto the officer.