The Keyword is 'Relatively'
First of all, I agree with you that this possibility--that the IRS targeted Tea Party groups based on news reports about new applications for 501(c)(4) status--does not mean there is no scandal here. What I said was "it might provide a relatively innocent explanation."
So here's why I used all those weasel words. On a scandal scale of 1-10 where 1 is a couple low-level employees acting like idiots and 10 is Ultra Nixon (Obama ordered it to punish his enemies), this explanation would be below a 10. Why? Because it means this might have started organically based on news reports.
Best case scenario for the IRS, they were paying attention to the news, which is something I believe they do all the time. (Anytime there is a big news story about someone's taxes, the IRS can use that as an excuse to investigate. I believe that has come up before, though I can't recall when exactly at the moment.) But even in this best case scenario, you still have to wonder how this progressed so quickly despite it being so obviously wrong-headed. Also, how it went on for so long.
But as you point out, it could also be the case that the news reports simply gave someone at the IRS an excuse to target groups they were inclined to target anyway. Why did they decide this was a problem right away? Why did they target the groups by name rather than behavior as they should have? These are good questions.