I think a Starling/Brown rematch for the IBF/WBC titles would have been a really good fight if it had happened in 1990. I think Starling could have still taken him, but it would have been a tough fight. Simon's style was made to order for Starling.
Brown's reign as IBF welterweight champion was strange. He fought pretty mediocre competiton from Trice until he finally got a notable opponent in Maurice Blocker. The first Trice fight was a war, televised on national TV, but looking back, it shouldn't have been such a hard fight for Brown. Trice wasn't a top flight welterweight. I haven't read the article you linked yet, but if I remember correctly, Don Elbaum promoted Brown and had trouble getting Starling or Honyghan or Breland to fight Brown. I guess the low key Brown was high risk. Elbaum was kind of a small time promoter for a world champion to be working with.