First of all, she's not beating Khabib in judo or any other combat sport. Let's just get that out of the way.
But...
If you know anything about her, this isn't the same as when people were talking about Rousey/Cain or any of that idiocy. Harrison physically is MUCH different than Rousey:
She is built more like a man. She's likely insanely physically strong for a woman. Still miles below someone like Khabib because it's just the way it is physiologically, but she's closer to Khabib than Ronda ever was to any 135 lb male fighter from a pure strength standpoint.
The other (and way more important imo) part of this is the fact that since she first phrases it as a question ("Am I gonna beat Khabib?"), that says she almost surely was ASKED about competing against Khabib (be it in judo or whatever). She didn't bring it up, the interviewer did. So, she gave her opinion. She thinks she could beat him in judo. She's wrong, but why is it a big deal that she has that confidence? I say good for her if she thinks she'd beat him.
Also, she is managed by Ali just like Khabib is. Pretty good chance Ali (who knows how to get media attention for his fighters) had a hand in setting this up to get Harrison more attention on the eve of Harrison starting her run to the $1m PFL tourney prize.