I bet this survey is related to the recent introduction of a similar service by Google. There’s nothing like competition to keep companies on their toes. Altavista apparently ponders the introduction of filtering/sorting options by date and geography (two of several suggestions I sent to Google earlier this week). Google added a "sort by relevance/sort by date" option to the beta, only to remove it a few hours later. I guess they’re trying different things right now, but this option makes sense (it’s in their Usenet service already).
Update: the sorting choice by date/relevance is back.