The person made them himself and donated them. No one asked him to make them. They should have refused them saying it goes against Judaism. At first I thought they made crosses since it's easy to hang things on a cross and then hung the Magen David on them. After all, that's the original function of a cross. Romans hung people on them for capital punishment. But now I see it was made by someone who makes crosses and just put a Maven David on the front.
Well, the article you posted said...
.A relative of one of those killed in the synagogue shooting reached out to him immediately afterward and asked him to make the personalized memorials — each with one coat of white paint, the name of a victim, a decorated heart and a message — in the shape of the Star of David rather than his typical cross design. By 1:30 p.m. Saturday, he committed to travel to Pittsburgh with the 11 stars.
As I said...no good deed goes unpunished.