I completely agree with absolutely everything you've said, Rizzle.
Talkative Hibari is definitely a completely plausible thing, but only when it's the mature, older version from TYL. There really wasn't any catalyst or reason so far, that we know, that would cause him to suddenly start acting like this.
And as for biting people to death, it's a very cute and lovely catchphrase, but when Hibari is using it multiple times per chapter it's a bit exhausting.