There are only two elements to this that are important. There is an investigation and that fact was leaked.

Just because the motivation for the leak is most likely political does NOT mean that the investigation itself is political.

If any of our agencies find any hint or evidence of spying they MUST investigate. Doesn’t matter who the perpetrator is or even what motivation there was to give these agencies evidence of spying.

Just as in the Plame business, the politics surrounding it have nothing to do with the fact that an investigation MUST occur.