Well, I share Roger's outrage at Piltz for saying Inhofe is claiming one potential criminal law violation. Inhofe is claiming three potential criminal law violations, at least (see pp. 29-31: False Statements Act, False Claims Act, and obstruction of justice, with some weird statement about an "OSTP Policy Directive" that is poorly written but probably doesn't assert criminal violations). A Roger Reader wouldn't know that Inhofe had said boo about crimes, where Roger only quotes Piltz and not Inhofe talking about such things, and Roger cheerily dismisses Inhofe's legal threats of any kind as inconsequential.
Not so fast, though. I'm not worried too much about the False Claims Act, which would only apply if climatologists got paid for work and didn't do it. False Statements and obstruction of justice, however, could come down to whether the climatologists misleadingly answered or deliberately failed to meet legal mandates to answer certain questions or information requests. Denialists are probably ready to call anything misleading and any omission deliberate. In a normal world this is almost never applied to responding to Congressional inquiries (when the tobacco execs said cigarettes aren't addictive, nothing happened to them), but the denialists are trying to shape a different world.
One would think that a political scientist like Roger would know that Inhofe will regain subpoena power as the EPW Committee Chairman if the Republicans get the Senate back, allowing him to cause endless trouble and to assert new legal violations if subpoena responses are deemed inadequate. If Roger knows this, he fails to mention it.
As for actual prosecution, it's highly unlikely so long as Democrats run the Department of Justice. Again though, I'd think that a political scientist would remember that the Bushies placed quite a few arch-conservatives at DOJ in the civil service, and those folks are still there and capable of making trouble. They'd most likely get shut down long before doing anything too serious, but those people could also make life difficult for scientists. And a still more serious issue, IMHO, is Inhofe's repeated mention of "debarment," which could make the climatologists and possibly their institutions ineligible for federal funding. No scientific institution wants even a whiff of that idea near them. The 2012 election isn't far off, and while President Sarah Palin is unlikely, she's not impossible. It's not over the top to worry some about this.
As Eli pointed out, there is a new McCarthyism, and it's from the denialists. Roger sees nothing to worry about though, so YMMV.