It's not proof that the whole field is garbage by any means, but it is at least clear evidence that a lot of respected names in the field are publishing crap that they provably don't understand. That's really not a good sign - there may be crap published in fields like physics, but it's not coming from the Feynmans, it's coming from the relative unknowns.

Secondly, while I haven't read the papers from which Sokal et al. take their examples, and don't know what they were about, I am certain that they're not trying to contribute to scientific knowledge in any conventional sense. I gather from a friend who studies this stuff that Irigaray was playing with the language of scientific discourse in some way. I haven't looked into it further. Some of the stuff Sokal derides certainly deserves it. One of his examples is where Irigaray's work is used to justify sloppy thinking about feminism in science education. That is definitely problematic and deserves to be dismissed out of hand. But generally speaking, Sokal picked out these quotes without clearly explaining their context and intent, and that seems problematic, too.

It tries to draw conclusions about the relative divergence times of different genes based on degrees of sequence similarity. This evidence is extremely weak, as there are much more likely explanations for the observed patterns of sequence variation, such as a shift in the selection pressure on a gene down the chimp/human lineage, for instance. Despite this weakness, they chose to highlight the sensational conclusion that human and chimp ancestors must have swapped genes through mating long after the presumed speciation time. This was irresponsible, because it caused a widespread public sensation when the paper came out.

it seems pretty harsh to lump it together with [1]...

I'm not lumping them together. The common characteristic is that they're both garbage. The conclusion of [2] is a subtler form of it but not to an evolutionary scientist: the problem with it was immediately obvious to me and many others as soon as it came out. And it's a more serious corruption of scientific discourse because it's a Nature article. The data the analysis was based on has merit, though.