I'm not attempting to defend the comments, merely to point out that the context is quite different from the way people are presenting it.
Personally, I think it is in extremely poor taste to bring flaws in another player's record up as he did. If Warne had said it in a less explicit way, like by saying "well, someone will eventually break my record, probably someone in a weak team who takes the bulk of the wickets for his side, or who plays the weaker international teams a lot more", it wouldn't have been such a problem. I think that Warne went on with it a bit too much, and it seemed really absurd the way he was making it completely obvious who he was talking about but still refusing to mention Murali by name. It was in poor taste, and came across a bit cowardly.
As far as the actual validity of the comments is concerned though, he's right. Murali does take a lot of wickets against Bangladesh and Zimbabwe (moreso against Zimbabwe, actually), and Warne hasn't had the chance to do that. Obviously he has the chance now and hasn't taken it, but then Bangladesh are a lot better now than they have been for the last 5 years, in which time Warne has never played them, just like Zimbabwe are a lot weaker now than they were when Warne played them last in 99. If someone on this board brought it up, I'd agree with them entirely, but I rather wish Warne hadn't done it, for the reasons mentioned.
Having said that, if Warne is in line for criticism for having a go at Murali for taking wickets against weak teams, I think Murali is equally so for bringing up the Indian thing as he does. Yes, fine, he has a better record against India, but I think it's poor form to attack the record of a fellow sportsman just to make yourself feel better about how good you are. And that goes for both Warne and Murali. If necessary, save it until after you've retired to talk up how great you were.