I think that response is exactly what you would want for someone playing Rigardo
. Christian Bale certainly can play someone about to go into blood lust mode. I have real difficultly looking at Johnny Depp and not laughing. I can't take the guy seriously even though he is a good actor. It must have been Edward Scissor Hands, or Pirates of the Caribbean, or Willie Wonka and the Chocolate Factory, or Benny and Joon, or... well pretty much anything I have seen him in. He could make an excellent MiB though as he can do mysterious.
Since Rigardo's human form is really just a cameo and then some digitized voice acting we could put Tom Cruise in there
. A whole role reversal from Top Gun with Val Kilmer and Tom Cruise talking. I'd expect Isley to call Rigardo a "maverick" and Rigardo to call Isley "Ice Man"
Though when he transforms and goes insane it might not surprise people. Josh Hartnett also might be an interesting Rigardo. Who would you pick as the current grown up Raki?