Watch your language!
(I still remember enough of my high school German to know that you're a naughty potty-mouth....)
You'll be fine, assuming it's not going to rain. Even if it is, you're replacing the thing in a day anyway. You're right. The boot is just to protect the cable from water/salt etc.
On the other hand, every single nut and bolt on your bike could come undone at the same time and it would fall completely apart the moment you reach 50 mph.
Not sure which.