I wonder what their definition is of not visiting a glacier. I would think that this would never happen on cruises visiting Glacier Bay, unless the whole day got cancelled due to bad weather or other emergency. Glaciers are more likely to be missed on the Endicott Arm/Dawes Glacier sailings. I've never been to Endicott Arm, but I've been to Tracy Arm a few times, and sometimes they barely get close enough to see a very slight, distant view of the glacier. So if they get close enough that you can barely see it in the distance, does that count as "visiting a glacier"?
In all of my cruises to Alaska (13, with 2 more booked this summer) we have only completely missed our glacier once, and that was due to a very unfortunate major emergency.