I'd say it's more a preparation of the electorate for the real anti-trust fight coming, to increase chances for successful regulatory action.... but maybe I'm just saying what you said with nicer words. Anyways, it's very smart politics for the President.
The fact that the 'bias' complaint is not particularly substantive doesn't really matter to the politics of the situation. Google, Facebook, et al can never produce evidence that "proves" their systems are not biased (closed code, closed data). People on the fence will become fatigued with their unverifiable and self-serving protestations.
The only people who have to say "trust me" are the ones who are not seen as trustworthy.
When the REAL substantive debate begins, it will be from a stronger political starting point. It makes it easier to solidify political support for anti-trust action, and increase the chances for successful legislation.
Not really a fan of the current administration, but holding out hope that something good (pro-consumer regulation) will come out of this. No thanks to Obama.