This is pretty preposterous. It is made worse by the fact that there was no indication when she bought the laptop of how installing Linux would affect her warranty support. Not that advance notice would have made it excusable, but it certainly would have affected her buying decision. According to the article, it looks like someone at HP is trying to help the consumer, here, but on an exceptional basis.
This doesn’t seem that exceptional to me. Sure, there are some support issues that HP cannot be expected to deal with when a user runs an after market OS, but those would seem to be clearly separable from issues of defective hardware manufacture. Even if the edge cases, like improper ACPI conflicting and causing battery damage for instance, at least being more clear up front would do everyone a favor.