Take a look at this quote from the first interview you linked:
Well pack it up boys, Joker can't happen because Sakurai said knives are too realistic to be included in Smash.
Oh wait.
There he is, wielding not only a knife but a realistic gun as well. A realistic looking gun that sounds and functions like one too - for all intents and purposes, especially as far as the ESRB is concerned, it is a real gun, canon be damned. If canon had mattered, Joker wouldn't be wearing his thief attire in the real world anyway.
Remember, Sakurai has said before that characters like Villager and Ridley weren't feasible additions. Things change, and taking 13 year old interviews as fact won't do us any good in this chapter of Smash speculation. Practically every fan rule has been blown away, and characters that were seen as jokes in the past are right here as part of our massive roster.
Rather than trying to keep ancient fan rules alive through ridiculous justifications (the same happened with Bayonetta and her "magical" guns), we need to accept our current reality:
The post-Joker world of almost endless possibilities.