I think the sentiment is understandable if the terminology isn't precise. Don't charge fees for non-optional things. Especially don't charge a fee to pay the posted price.
I missed that this happened, that's great news. When I saw a few places get away with no longer accepting cash "for the convenience of our customers and the security of our staff," I figured that it was only a matter of time until everywhere else that wasn't doing light tax fraud followed suit.
Tangentially, I'm also pleasantly surprised how easy it still is to buy a physical MetroCard. My understanding a few years back was that contactless payment would be the default by now and if I wanted to buy a physical MetroCard, I'd no longer be able to do that at stations but I would instead need to go to "select retail partners" to do so.
As a guy who used to have to take a zipper bag full of cash to the office safe every night, the convenience of the customer part may be laughable but the safety of the staff part isn't. Offhand I can't think of a more effective way to bring back 1990s mugging culture.
There's a difference between the letter of the law and the word of the law. Having experienced both places I can say there is a difference in how things are run and regulated and if they call it legal tender or whatever it doesn't matter. As a customer it does matter because I end up paying the junk fees so please don't patronize me for saying it.