I installed the patch jar because its not a bad idea, whether or not it's actually needed (which I doubt anyway) is another question, but in my opinion I think it's just a good idea...
The exploit isn't cause by the jailbreak method the jailbreak method exploits it's presence. SO it's present in ALL devices running 4.3.3 Until you install the patch.
Which means, yes even if you used redsn0w you should install this because the exploit is open to you which is apple's fault.
Huh? All this is is to patch the hole used by the exploit once the device is already jailbroken. This will protect you from malice if anyone else should try to use this hole for devious reasons.