I bought the Moonlander a year ago, and I completely regret it for the reason you mention: the horrible palm rest. It's wobbly, and when I contacted them, they told me that in the "ideal setup", my wrists aren't support to rest on them. Palm rests where you can't rest your palms.
I'm really frustrated, because I love everything else from this keyboard. But those wobbles really do make it unusable.
What they probably meant was that your wrists shouldn't be supported WHILE typing. You should only rest them while they're actually resting. Usually wrist trouble signals that you should be sitting higher/move the desk lower.
I'm really frustrated, because I love everything else from this keyboard. But those wobbles really do make it unusable.