You're absolutely correct. The video someone posted had the breaker bar wired in or whatever( I think it was because it was a front mount rather than the side mount like we have), but stay away from where the action is. I don't bother to wire it down and definitely don't have someone hold the breaker bar. Something could come apart and cause some serious personal damage. The breaker bar could fail, the socket could split or just fly off. Justanothermechanic also stated he hit the starter for a second. Just bump it as it literally means. All the procedure is doing is releasing the torque not removing the bolt.I am sorry, but I have to say this.
It is absolutely ridiculous that OP had someone push on the breaker bar. The worry is exactly that something will pop back and hit him/her. So STAY OUT OF THE WAY!!!
Just think, the starter is stronger than you: you couldn't open the bolt, but the starter could and did.
For the next person who searches and finds this thread, I sincerely hope you do more research than OP, and from your research you realize that although this is widely recommended to work, this is considered a dangerous method.
In your research, you may also read some people suggesting leaving a little slack for the breaker bar to move/swing a little bit, and you put some padding on the control arm.