Specific objections to trying to cleanse all old materials is exactly the issue. I. And others specifically object to.
First, it's just not going to happen. This specific publication is just one obscure example out of hundreds (thousands?) of things published over the past half century.
Second, do you really think there's a reason to stop here? Evil elves in blackface where men are subjugated by overly well endowed dominatrix women is just peachy? Or even the description of half orcs in the 5E PHB?
Third, it's simply never going to happen. If this petition gained steam the only result would be to shut down sales of all older materials. There's simply no business case for it.
Even implementing the suggestions for just this one publication likely would not have a positive return on investment.
EDIT: I brought up Huckleberry Finn being banned because of why it's being banned. It's being banned not because of Tom's relationship with Jim which is quite positive for the time. It's banned because it uses the "n" word to describe Jim at a time when that is simply the term that would have been used. I object to censorship based on modern sensibilities, especially when looking at the entirety of the publication and the context in which it was published. This book was breaking ground at the time it was published. It could have been better, but should be considered in light of the gaming culture at the time. Even if that reflects some negative things.
So yes people have real, specific, objections that you are choosing to ignore.