I do agree, his "big mouth" got him in trouble. He has no obligation to tell the media anything, and he should know that the media is as much his enemy as is the state of Florida.
Crump is establishing that he is opposing counsel, for purposes of avoiding being deposed in the criminal case. I think filing the settlement agreement is unnecessary for that purpose, as his proffer that he is counsel for the Martins and he intends to sue Zimmerman is likely sufficient to establish him as "opposing counsel" in that sense.
Wouldn't a proffer from O'Mara that he does not intend to represent Zimmerman in any such civil suit trump that Crump proffer???