Here's the episode, and please listen to a bit of it, at least. I don't want anyone to misunderstand my very mild criticism.
Basically, they talk about how Harris is being described as a sensible moderate, but she's definitely part of the Warren-esque deep left wing of the party, approaching Sanders' far left on policies and her voting record in the Senate. They take particular amusement at her being described as too right wing.
My understanding of the criticism (I think) explains both why Biden would pick Harris, as well as why she ends up with these confusing political descriptors – it's not too confusing (to me), and hearing essentially the same ideas come out of Josh Barro's mouth months ago certainly makes me feel reasonable.
The analysis starts with observing something: Biden may well achieve more than any other president if he can reverse the policies he spent years enacting. Not just voting for war in the Middle East, not just rolling back the draconian and unnecessary crime bills, but also reducing the footprint of the American spy agencies, and maybe ten or twelve other mistakes made during his tenure (I'm not even going to bother figuring out whether he supported the recent creations of the DHS, the TSA, or ICE).
But he's a rusty weather vane. He'll do whatever will give him access to power. There's no big surprise there – he's the living embodiment of The Median Voter Theorem. Every statement of his is calibrated so that it wins him more votes than it costs him, and if there were voters out there who weren't interested, and he could pick them up with an additional statement or proposal, he would. He has, as far as I can detect, no principles, but that can be sort of reassuring – he won't stray too much from pandering.
Kamala Harris is the same way, but worse at it. She went too far left in the primary, floundered and was confused about her own policies, and the whole thing exists in stark contrast to a prosecutor who invented false confessions, and wanted to arrest parents for having truant kids. When she was a prosecutor, she thought that's what people wanted. Recently, she thought they wanted someone like Warren – that's certainly closer to the median voter in Californian democratic Senate primaries. But it misunderstands national appetite for those policies.
This is why she is described as a moderate, or even pretty far right – because people take her attempts at being a weather vane, or her earliest, non-strictly-political activity as indicative of what she wants. While this characterization is pointed and has a specific viewpoint, it isn't unfair: real life isn't like high school debates where you just take any position and it's all forgotten later. You're expected to say what you actually think. Lots of people are reasonably convinced she's lying to them, and they're trying to see through the smoke.
Of course, there is nothing behind the smoke for Harris. Only lust for power. But that's how the system is supposed to work, I think, as long as Congress engages is rigorous checks and balances. She's applying for a pretty minor government job anyhow.