Department of Unintended (But Completely Obvious) Consequences
The presidential race is not over, but at this point, Obama has a better chance of becoming president than McCain, and as a result, the questions ought to be going toward him as much or more than McCain -- questions not of tactics but of substance.
McCain has been criticized for raising questions about Obama that were seen as questioning his patriotism or his commitment to the values the country holds dear. But there ought not to be any moratorium on asking hard questions of both candidates right now, and especially of the Democratic nominee who sits in the pole position heading into the final three weeks.
Balz is not only suggesting an overt double-standard, he is suggesting a glaringly illogical double-standard.
Say the press does (or, if you prefer, continues to do ) what Balz suggests and scrutinizes Obama more closely than McCain. What then? Well, potentially, that scrutiny results in John McCain beating Barack Obama.
In which case, in an attempt to ensure that the next president is thoroughly scrutinized, Dan Balz will have helped elect the candidate who, because of his own suggestion, has not been scrutinized.
I know this is a crazy idea, but if reporters want to make sure the next president has been thoroughly scrutinized before voters make their decisions, they could thoroughly scrutinize both candidates.