There's nothing wrong with the term, it succinctly conveys the limited functionality of this software.
Words aren't sentient and as such they cannot be ableist, only people can. It's perfectly clear that the author didn't intend to offend, demean, or discriminate against any disabled person with their choice of words, they were merely writing about their own software.
That said, I like the frugly approach. The cosmetic upgrade approach in Fortnite the author mentioned is also implemented in a new game I've been playing called The Finals. It is nice not to have winning behind a paywall.