100% agree that this is NOT a spoiler. A spoiler is about watching the race but knowing the outcome before the end, so the excitement factor is gone. In this case the Froome thing was known before the race even started. If you want zero information about what happens between the end of stage n and the beginning of stage n+1, you need to lock yourself in a closet with no electronics or internet. This isn't even close to being a spoiler and there certainly is nothing "to be careful about" here.
dave