In one of the internet forums, instructions were given to use a 'fresh' computer to store the offline MEW.
I can understand isolating the computer from internet after storing the offline mew. But does it have to be
an internet-free computer before, as well?
Running MEW offline makes you safer than login in through the web browser by entering the MEW web site's URL. If you mistakenly enter a typo you may ended up with reaching a phishing site. Sometimes you may Google MEW keyword and might click an ad which claims as MEW site and get scammed. You can avoid such incidents by using MEW offline.
There is no need for a fresh computer if you have a virus free computer which is not connecting to the internet or external devices such as USB pen drive.