It sounds to me like the real problem was that the riders would be 37k 'on their own'. 37k in which stuff can happen that changes a Giro.
[I disagree with some posters that Wouter's death, tragic as it is, on a road that wasn't a noteworthy -by cycling standards- safety hazard by any stretch of the imagination, should be reason to forego roads like the ones they are now deeming a no-go zone from now on. All the more with the additional safety that was put in place. 'Ride to your ability' is a judgement that is part of pro-cycling too. ]
A few days ago it was deemed safe enough, and this 'no cars to support' reason was suddenly pushed in at a time when it no longer could be solved with motor bikes with material, etc.