Do you really think it's that simple? Do you think, somehow, that students couldn't figure out how to similarly disable whatever software is running to active the webcam if they had known about it. The machine is user configurable. Similarly, having the source is no guarantee of security either unless you think mystic code audit gurus are going to step through the portal from geek nirvana to audit the entire software loadout of every system. As we have seen on numerous previous occasions, having the source is no guarantee of security.
All that is needed is the ability to audit what external connections a program is making. And, since this was discovered there is a class action suit against it. Presuming they win, which imo seems likely, I doubt any other school district will try this.