This is the requirement, yes. Modern Vespas are notorious for having the sidestands fold up when parked, in high winds if covered (cover is a sail; bike rocks, unloading the sidestand, which promptly retracts and drops the bike). These sidestands can often be modified to not retract automatically, but that leads to the pogo-stick problems we all know and mock mercilessly.bikes that do not have sidestand interlock switches are those that come with sidestands that automatically retract -- spring up -- when the weight is lifted off them (as in straightening the bike upright, as you get on and prepare to ride).
The solution, of course, is to use the centerstand whenever feasible. Their sidestands have almost always been optional anyhow.