What do you mean "pull that blog back"? If you mean cause it to suffer in the rankings, I'd stay well away from that line of thinking. Launching attacks, whether overt or covert, has a way of coming back at you.

The far better approach is to simply out market and out-SEO them, to rank better. Plus, if it really is a spam site, chances are it won't stand the test of time.

My 2 cents anyway.