Do all XC90's have xenon headlights? If not, I suspect that the manual was written for those without and someone forget to cater for the xenon variety. Blanking off xenons can cause more dazzle than one is trying to avoid.Whilst I appreciate that generally it is not sensible to mask xenon headlights, it can't be universal since my Volvo XC90 manual advises me to tape them; and provides a template.
So check with your manufacturer/dealer.
Mike A