Because Ronde van Limburg is now on Wednesday.
Flanders Classics wanted the Ronde van Limburg to close the cobble season and Brabantse Pijl closer to AGR to open the Ardennes season. They thought both would have a better startlist. I am not sure if that works out as they wished.
Muur and Bosberg would only be possible if the start is in that region. A Brussels newspaper opted that the race would be heading towards the birthplace of Remco. Muur and Bosberg are not very far from Schepdaal. Also, the frontier with Wallonia is nearby.
But the hills from Brabantse Pijl...
The finish will be as close as possible to Brussels centre. There will be several laps in Brussels, showing most of the historical buildings. Before those laps they will go to Flanders (probably direction Remco's birthplace (with maybe Muur and Bosberg) andr direction Overijse (with the hills...