It doesn't make sense that it would be anything but a bug. The pages without links are both Google properties... the US and the UK versions of the Google Adwords Keyword Tool. We could perhaps get a conspiracy theory going if they were competing tools.
Probably more a glitch than a bug. I've tried the search several times in different browsers and haven't been able to reproduce the problem. From the screenshot it appears that you're logged in with search history enabled, though I don't see what that might have to do with it... unless you've shown a strong preference for clicking on results without links. ;)