I didn't see the game but...
1. I don't think that bunting for a hit with a no no in tact had anything to do with the earlier antics.
2. The game was still close. You try to win any way you can. To win, you must score. To score you must get on base (or hit dingers). You get on base any way you can - take what the defense gives. In this case, I don't believe it goes against unwritten rules.
3. If the game was further out of reach, bunting for a hit would go against unwritten rules. Unless it was a blowout, I personally don't like this particular unwritten rule. A good bunt is just as valuable as any other form of base hit. Even if you're down five or six runs, if this is how you can best help your team offensively, I don't think it should be frowned upon just because the pitcher hasn't yet given up a hit. You have to start the offense somehow.
Now, if it is a blowout and the bunt is layed down for the primary purpose of breaking up the no no, that's a different story.
JMO... never liked that particular unwritten. Big rallies can be started by a bunt or two and MLB doesn't do it enough. Always a pet peeve of mine - I know I'm the minority on this one.