I don't think it's ridiculous, it's just they might not necessarily care enough. They will consider it a bug if there's enough uproar, for now there are just a couple of unhappy users here and there, no reasons to revert something that presumably took a lot of work to implement, especially if the fix takes more effort than the original implementation (I wouldn't be surprised since we're talking about performance differences between browser engines).
I didn't say they that they couldn't have accidental bugs.
I did note that they'd normally be able to rollback a deploy with problems.
Why do you say that's ridiculous to comment?