Valve already provides the information on their site, anyway -- maybe with a focus on the top games, perhaps, vs. "every" game on Steam, but it's still there: average users per day, tech support calls & refunds per day (& by hour), their hardware survey, etc. And I would imagine that developers with games on Steam already have access to the stats for their particular games (including daily usage & purchase totals). So, aside from a "lookee here!" to the general public, I really don't see how this website was of any help to developers (3rd-party or otherwise).
Not to mention my question: the API that he used to access the Steam software distribution service, a) was this an API he (or someone he paid) developed or something that Valve developed in-house for developers to use, & b) did he have permission from Valve to use it for this purpose? I could see, for example, Rockstar Games using the API to access Steam for information on Rockstar's own games...but I would imagine that Valve would have frowned a bit on Rockstar having access, say, to the data on Firaxis's or EA's games (& vice versa), as that smacks of giving them "insider information". If they were to frown on that, I can imagine they wouldn't be too happy about some 3rd-party spectator getting that kind of access.