Yeah if you were to get a file and hack out the middle of that crack it would stop the rattle. I'd advise against using any sort of drill on that cymbal because if its not done properly you can damage the temper of the metal and the crack will go in different directions.
Just use a flat metal file and slowly erode that middle part between those two holes, and you're OK.
Or not... as Enrico said, the holes are indeed stopping the crack from spreading.
But one thing also to consider is that the cymbal will end up with roughly that same position under your stick so maybe examine the way you're hitting it as well as the angle at which you set the crash otherwise you'll pop another crack.
Ya - I didn't really look at the picture. If the crack goes all the way through, the edges are probably going to buzz.
Like everyone's saying, the holes are already there. I'd just enlarge the crack and make sure all the edges are as rounded as you can get them.
If you have a dremel tool with some attachments, you could do something like this (quick crappy graffitti, just to illustrate):