I doubt Kristol said electing any of them would be a mistake. It was more that they couldn't be elected (apparently Romney couldn't either, but that's another story).
Kristol has a valid point here. NSA snooping happens whoever is president. If you find some connection to the administration's political activities, there's a valid connection to the IRS scandal. If it's just NSA internal national security activity tying it in to other scandals may weaken critics of the administration.
It’s not conflation to see the IRS and NSA scandals as each being symptomatic of an out-of-control state.