If you don't bother setting up an internet connection on the netbook it will be fine.
The stark warning about rendering the netbook unusable applies only to the procedure for setting up such a connection -- once you start the setup procedure for an internet connection you must not cancel or interrupt it.
Since you are not going to bother with that procedure you will do no harm.
My wife bought a Dell Inspiron 1018 netbook and external DVD ROM to input software. Page 14 of the Dell guide states an Internet connection is optional and page 9 says a procedure screen will include setting up of an Internet connection. Warning is given that interruption may render the computer unusable. I would like to know if avoiding an internet connection can be done without danger to the operating system.