It's very simple (and probably says as much at the top of the hub that has been removed): All you have to do is contact HP staff and they will help you figure out why the hub has been unpublished.
You can do that here: http://hubpages.com/contact_us/
I've had hubs pulled down after having been up for a long time. Google changes its rules, and so, when their rules change, hubs that might have been in compliance at one point in time, suddenly aren't. While I sometimes feel that the reasons for this are absurd, it really doesn't matter what I feel, because HP is a privately owned, for-profit company. They don't have to be "fair," nor are they required to grant us the "freedom of the press." They aren't the government, and you and me ain't the press, at least not exactly.
So, tell your friend to take a breath and calm down. Tell him/her to read what it says at the top of the hub that was unpublished (which probably has a link to the part of the Terms of Service from which the violation is being identified). Do what it says there. If you can't modify the hub to meet the standards, or are unwilling to, then take the article and publish it somewhere else. If none of that works, and you still need assistance, email HP and let them try to help you out.
Just remember to be polite. Having a hissy fit and screaming about "injustice" won't get you anywhere.