They accommodate because you have a pre-booked paid activity and have no control over your VQ time. With only a 1-hour return window many dining reservations conflict as well. I don't see why so many people get up in arms about the fact that Disney as has been widely reported will accommodate around other paid timed activities they sell.
Good for you that the 1pm drop works for you - it may not work for all. What I say stands - she's likely to be fine based on the vast majority of reports but if she's planning on being in the park until closing - the 1pm will likely be fine but 1pm drops are also iffy if the ride has any problems that day. Either way involves some risk.