There are varying opinions on if the swaybar needs to be disconnected for an alignment. I tend to be of the school that it does not need to be disconnected.
My reasoning is that, in theory, there should be zero force on the bar when the van is sitting level. This is pretty easy to achieve by just shortening or extending the sway bar links when level. I have done both the front and rear on our van. If even it makes it has no input on the alignment by changing height so connected or not is identical.
If there is force on the bar it means it is supporting some of the front wheel weight on one side and reducing it on the other side, making one side higher and on side lower than with the bar disconnected. Having the sides at different heights with the bar off changes the settings from normal driving setup with the bar connected.
Why would you want the alignment to be correct for the van in the non driving situation with it disconnected and off by some amount with it connected?
If they are trying to level the front end by shimming springs, adjusting torsion bars, or adjusting a coil over shock absorber, they do disconnect the bar as it is needed. I have never seen any shop disconnect and swaybar before any alignment I have gotten.