How on earth was that road open for traffic on the opposite lane during a sporting competition? Alex, you are a hero and an inspiration, and deserve much better than this...
For longer distance cycling events, it's not uncommon to have "rolling closures" where only the direction of travel for the racers is closed via police escort, while the opposite lanes are open. I've done some road races on my bike where they enforce center-line rules meaning that you cannot cross over the middle of the road to overtake, as cars may be coming the opposite direction.
That said, if you have a fast downhill, it makes sense to me that you have to close the entire road because of the very obvious risk of a cyclist either misjudging a corner or having a mechanical failure. Straight, flat road, easy enough to stay in one lane, but not on a twisty fast section.
Edited by Dan333SP, 19 June 2020 - 18:42.