I am a dog professional. And you’re article isn’t true at all. And I want to explain you why. Being both a trainer and researcher I experience that a few dogs indeed react to black people.
The reasons you provide are xenophobic and clearly racist. First of all, those dogs also respond that way when there is no owner around. Second you mention you deliberately lock eyes with a dog. Which isn’t natural in any animal expect when you want to provoke.

But again, the real reasons. First of all dogs are considered family in the dominantly white Western cultures. In African cultures when people have dogs they are for guarding purposes. Something Trevor Noah explains in his book quite well and I was surprised to find it there.
Far less black people have a dog and when for instance people from Somalia and Eritrea come to my country (The Netherlands) most of them are surprised how we treat our dogs and a lot (especially the older ones) are afraid of dogs. Even in countries like Kenia which are far more dog friendly they find it weird to have a dog IN the house. While they love dogs in the village.
Dogs learn by association. Meaning that they relate similar behaviour to similar cases in the past. So if 60%+ or even more (which is my unscientific estimate based on personal experience) act anxious around them they associate black people with untrustworthy/anxious/unstable behaviour.

Now I have three dogs, and moved to a town with only a few black people. Some eastern asian people. None of them are afraid of dogs and very open (not locking gazes or acting anxious) Result: none of my dogs react any different. Because they react to behaviour and there is no way in this case to associate a specific behaviour with a specific skin color.

Also there is scientific research done on the subject.
https://www.psychologytoday.com/us/blog/canine-corner/201602/is-it-possible-dog-could-be-racist