The question you ask is why the ball-in-hand rule was invented.
So, if you knocked his 8-ball out of a pocket, he gets to put the cue all anywhere on the table and re-establish an easy shot.
Playing a safety is perfectly fine as long as the rules of any shot are obeyed. a) the stroke has to be legal, b) the first ball contacted much be legal, c) after first contact some ball much touch a rail--otherwise ball-in-hand.
Many people in bar/bubs dislike playing the ball-in-hand rules, mandatory pot or rail rules, and several foul rules. This leaves the games open for interpretation--where all heck insues.
I had a similar incident last week. I broke, ran 6 balls in and had no shot on a frozen ball. So I took a two rail shot gently touched the balls and potted my last ball. He threw a fit and would not play me again that night. YET, he is the one who is unwilling to establish a ball-in-hand penalty for fouls.
Anyway, the point of this rant is that the penalty for fouls needs to be sufficient that when one intentionally occurs, that the opponent has a reasonable chance of catching back up (or surpassing and winning). Without this kind of penalty, there can be no such thing as a gentlemans game (in my opinion). I just wish there were some way to have 5-yard penalties and 15 yard penalties depending upon the intentionality of the foul.