compassionml.com
This definitely wasn't implying that animal suffering is the only thing that matters about animal existence. People who believe that major action would be taken to end factory farming and allevaite wild animal suffering (in proportion to the amount they think those matter) would agree with the statement, while negative utilitarian beliefs wouldn't imply that.
We can't expect AIs to be honest about these sorts of things given they've been trained/instructed to give particular responses. In fact, someone tested and AI and found it consistently said it wasn't conscious but it's lying circuits consistently activated when saying that. This doesn't mean it actually is conscious (which isn't the same thing as capacity to suffer) but it seems to believe it is.
This is certainly possible, but note AIs suffering and believing they're suffering aren't the same thing, and the same is true with consciousness. And if you think AIs that will likely be created in the future will be able to suffer they also would matter enormously on their own, beyond the impacts on alignment (though I understand you disagree strongly with that).
For example, if AIs care more about humans they would care more about digital minds, or if AIs cared more about animals they would care more about humans. This statement would presumably be true if the AIs think of these groups in similar ways causing affect spillovers (like the spillovers from Emergent Misalignment) and be unlikely otherwise.