Runescape Account sharing

So I recently got permanently banned for Macroing, even though I wasn't, but that's another story...

Basically my friend that I have played with for years wants to know how safe account sharing is as we were going to share his account so I can still play the game.

He lives in Australia and I live in the UK, so is his account going to get flagged for sharing or anything like that?

Thanks

 

I shared my account with 4 people at one point, we all lived in the U.S but were a couple hundred miles away. One day when like 3 of my friends had logged in on it and I logged in on a vpn as well the acc got locked. After I recovered it there wasn't an issue for months. I don't see it being a problem if you acc share, your acc may get locked tho.

 

Ok, what did they say the reason for locking it was?