I don't follow your logic. I didn't see anything in the story that indicated that the deal was exclusive.
Twitter certainly wouldn't want it to be - they're trying to increase reach. In theory, I can see how Google might want the advantage of an exclusive data source. However, in practice I suspect Google thinks they can get enough of an advantage from using Twitter's firehose better than their competitors do, especially since paying extra to get Twitter to lock out competitors would invite even more antitrust scrutiny.
With the Google/Twitter firehose deal, Google's competitors have lost a potential advantage, but that doesn't mean they've picked up a corresponding disadvantage.
Twitter certainly wouldn't want it to be - they're trying to increase reach. In theory, I can see how Google might want the advantage of an exclusive data source. However, in practice I suspect Google thinks they can get enough of an advantage from using Twitter's firehose better than their competitors do, especially since paying extra to get Twitter to lock out competitors would invite even more antitrust scrutiny.
With the Google/Twitter firehose deal, Google's competitors have lost a potential advantage, but that doesn't mean they've picked up a corresponding disadvantage.