Why the tagline "It's nothing personal" for "Terminator 2"?

"It's Nothing Personal", as seen on the poster just above the movie's name:

This was possibly meant to indicate the nature of machines. Schwarzenegger, as you may recall, was the "bad" terminator sent to kill Sarah Connor in the first movie. In T2, he was sent as the protector of Sarah's son, John. He was programmed with a mission, and that mission has nothing to do with emotions. It's cold. It's uncaring. But it also has an aire of bad-assery to it.

Also, if I'm not mistaken, Sarah says something along those lines (maybe verbatim) when she goes to kill Miles Dyson in an attempt to create a different timeline where Skynet doesn't exist.

After finishing filming The Abyss, James Cameron was asked what his next film was going to be. Filming The Abyss had been a very difficult process and the last thing he wanted to do at that point was to undertake another big, complex film, so in reply he said "something personal".

His next film after The Abyss was T2, hence the tagline 'Its Nothing Personal'