using WiFi for side loading of books

I have now WiFi off all the time.Main reason is that I do not want any updates from Amazon. I am happy as my PW is now.

I load all books using USB connection from Calibre.
I like to use KoReader and load and sync over WiFi.

Would it be required to de-register Kindle from Amazon to avoid anything be pushed from Amazon?

Would it be 100% workable solution?
Thank you for your kind answer.