Modern woodworking glues are extremely strong. I have no doubt that a well fitted, glued miter joint top would work fine. There is really no reason to miter the top front panel to the top, if you want the ADA stand appearance. If you miter all front joints, it is really nothing like an ADA stand, it is just a box with a door. My preference when I have that situation is to use a dado joint at the top, with the lip of the sides that stick up above the top itself being about 1/16" thick. It is then just barely visible, and if that corner is relieved at all, it vanishes. I have used that joint on many cabinets because it is so easy to make it fit perfectly.