There is a simpler explanation: Russian is probably the only Slavic language most Americans know about.
My grandparents and parents and siblings all learned Ukrainian in school during Soviet times. This is in what now would be considered a predominantly Russian-speaking part of Ukraine btw.
Hearing Ukrainian for the first time, if you're Russian, sounds like you're hearing a Russian dialect you never heard before but understand 90% of, bar some words you've never heard. The languages are that close.
Polish, otoh, would baffle a Russian at first, you'd grasp quite a bit but you know you're hearing a foreign language, Slavic but foreign.
For example it shows EN/DE and EN/NO as having equivalent distances (49) when obviously EN/DE are much closer than either is to NO (in any holistic comparison of the three languages). It also shows IT/FR as being significantly closer (31) than IT/SP (40) when that's also plainly not the case -- again if we consider the distance between respective language pairs holistically (which includes a whole lot of other factors like phonemic footprint, meter, etc).
In short this reads like pretty much the kind of post one would expect from a "brain candy" site like this.
Less harshly (assuming good indent on the author's part), it demonstrates the pitfalls of relying on a single score (which in itself can be subject to all kinds of weighting and sampling biases) simply because it's a "score" and we're all supposed to be "data-driven" in our analyses these days.
But again -- nifty diagrams, and they do at least give a feel for the topic of mutual intelligibility and language distance (even if the scores themselves don't seem to be particularly meaningful).
From the other side, my Czech friends told me that Polish sounded to them like something from deep antiquity. Like reading an ancient manuscript where again you get the words but no sane person these days would use them like this.
Because Americans are so good at distinguishing Slavic languages by ear in a noisy room?
I live near a Russian Orthodox church. People complain about the congregants, but mostly about their parking. A house opposite the church as a Ukrainian flag prominently hung; on the other hand one of the congregants has a sticker of the Ukrainian flag with the don't-tread-on-me rattlesnake. I don't think most Americans care enough to be rude to Russians.
We visited St. Petersburg some years ago, probably 2012. I very much enjoyed the visit. Everyone seemed to be much too preoccupied to give a damn where we came from. The cases of Griner, Gershkovich, and the NCO in Vladivostok do make one wonder about the prospects of American tourists.