humble bundle region locked?? Saints row 3

If you are outside of Germany now yes.

However, that might be a different case if you yourself access his account and activate it (if you are outside of germany).

It is not. First off, account-sharing is prohibited (except through Family Sharing); second, account-related matters are determined by the account, not by whichever user happens to be on it at the time (which is intuitive, given that they only want one user to ever be using it). Furthermore, it'd be quite the challenge to validate whether a friend used the account, versus the account holder using VPN or other means to bypass Steam rules- so, in other words, it's not something Valve would do to begin even if the other factors weren't in play.

Account-trading is also against ToS, but at passing consideration, I wonder if you making a new ROW account for your friend to activate ROW games on may not be the best option for them in the long-run- then again, some games are install-locked as well as activation-locked, so that won't always work.
At the very least, if that account gets suspended, it wouldn't affect their main account..

Even if you log through your friend's account, you'll probably still wanna use VPN and paypal [versus credit card], as I believe (by way of comments on SG) that Humble determines your region by a combination of IP and purchase information. Again, it'd be easiest if you can get Humble to set up the gift for you manually, and that really does seem like the kind of thing they'd be willing to do.

But yeah, I'd say going through Humble to purchase a different version is still a better option than taking risks from Steam, regardless of how (un)likely Valve may be to follow up on such things.