There are plenty of other situations where you supposedly cannot fly standby. Since agents don't always intently study your reservation, often you can fly standby when you officially cannot. Hotwire is probably the same here -- standby if you want, but don't get your hopes up too much.

On the other hand, Hotwire (and Priceline) are the closest thing to standby tickets you can buy other than actual standby tickets (didn't work when airlines tried it in the past). So trying to fly standby on these kinds of tickets almost makes sense.