Honestly, that's not a bad solution. A player should really consider all options, in accordance with their current skill level or comfort zone, before committing to any shot in situations like this. If you know your odds of getting out here are worse than your odds of playing a good safety, then a safe is the way to go. Doing what it takes to win is what's important.
You'll get murdered, long term, playing safes against anything over a fargo 600 from positions like these, possibly all the way down to about 550.
You allready have good position and a four ball run out. ANYONE can run 4 frickin balls. Seriously, if you are an underdog to the 4 ball ghost, which is close to what this is, you have to be waaaaaay down in the 500's, possibly in the high 400's of Fargorate.
So lets examine the position tactically: You have four balls in fairly easy positions, at least nothing is tied up. The 7 ball is deceiving, getting snookered means you horribly botched the position play, even if the 9 wasn't there. Now, lets disregard that and say you play some sort of safe on the six.
I don't trust anyone who can't run four balls to lock up this safety, I'll bet they'll leave a simple one rail kick or jump. Best case they get the 6 down table and the cueball behind the 7-9. So what are the outcomes:
1. The opponent kicks, makes a hit and makes the ball.
2. The opponent kicks, makes a hit and leaves you snookered (unlikely but possible)
3. The opponent kicks, makes a hit and leaves you tough
4. The opponent kicks, makes a hit and leaves you fairly easy (like the position you allready have, though it's a good chance you have to travel further)
5. The opponent kicks and misses, giving you ball in hand on a ball that's now further away than it was. You can give yourself a good angle on it, but really, the problem with the 9 still exists from the other side. You need a good position on the 7 to get to the 8 easily without the 9 interfering in some way.
So what did you really accomplish? You sacrificed an easy position for a CHANCE at getting an even easier position. As seen above, there is a high likelyhood of this going wrong. Someone making a one rail kick or normal jump is not unusual at all. In those cases you may never get back to the table again. In several other of the outcomes you make yourself an underdog. For what? Because you're to yellow to play a perfectly normal, easy position shot? You still have to run 4 balls to win and I sincerely doubt it will be very much easier than it allready is, even with ball in hand. I guess if you snooker the person, leaving the 6 close to the 7 and still prevent him from hitting it, you could make it easier?
All of this is for naught, I fear, since a terrible player will get in trouble from the 7 to the 8 and the 8 to the 9, at least as often than he'll mess up the 6. Even with ball in hand on the 6, those two transitions have to be negotiated. If you're going to play safe here, I suggest doing it on the 7. At least then you can move it down table towards the 8 and make that transition easier, that is if the opponent misses the kick. If he does hit it, then refer to the outcome chart above. The outcomes are still very likely negative for you in that case.
TLDR: If you're a good player, you should get out as it is. If you're a bad player, you can't really benefit much from safing on the 6, you must safe on the 7 to get any benefit at all.