I explained why. If the battery is disconnected, conductivity doesn't matter. If it is in but the machine is powered down, a lot of it will not be able to short. If you are disassembling a computer and cleaning it bit by bit, of course you don't use water. In an emergency situation, where you have an acidic liquid sitting on thin contacts, you want to dilute it as quickly as possible before it causes corrosion. The one computer I have seen destroyed by a spill was done in by corrosion, not by a short. I would maybe spray the keyboard while the machine is upside down so that everything drains back out quickly.