Techland included all 10 content drops in the March update to the offline installer. From what I gather, the game checks your computer's clock, and if it's set to after a certain time and date, the content is automatically unlocked. Others on the forum have said that the content showed up on its own. I don't have the game installed because I was waiting for the final content drop before playing it. The best way verify that the content does not require internet access is to install it, block internet access for it with your firewall, and see if it shows up.
ok, so i've downloaded the game, and tested it without internet connection and galaxy. i have limited information as to how to tell if it exists and where to look for it, or if it simply doesn't exist. first i had a look at the "what's new" section. there were eight items and no mention of content drop 10. i had a look at my buggy and i couldn't see the "desert fury". i had a look at my stash to change my character. there were 3 other playable characters (4 including crane) but no mention of the "badlands rider". i have finished the games but i haven't done all the side missions and i don't know if this is a requirement. most likely, content is not present.