Where's the claim the data is fraudulent?
The claim is the data is missing. This is not the same. The presumption that it did exist is the reasonable conclusion, however, for it to be scientifically useful, people need to be able examine the data from the beginning. Correction techniques are routine applied to data across a wide variety of sciences, but are themselves something legitimately subject to scientific examination due to their intrinsic danger.
For all you know, the corrected data underestimates warming due to use of bad correction methods! How would you prove this, though? The data is missing.
Here's a very important point: This isn't about global warming or the skepticism thereof. This is a story about scientific malfeasance. Going to town defending people who can't produce their data, in accordance with the basic scientific principle of reproducibility, is an enormous flashing warning sign that you are deciding positions based on politics and not science. The scientific principle is clear: The data should be readily available for others to examine, full stop. That examiners may challenge it is a feature of the scientific process, not a bug!
There's really no room for debate on this, unless you are willing to admit up front that science is not a relevant consideration to your position, in which case, yeah, sure, go nuts defending the guys who won't produce their data. But you should be aware you've left science behind.
Am I personally a skeptic? Yes. But this isn't why, nor do I consider this evidence of my position. It is just plain scientific malfeasance of the kind that can pop up anywhere; since it's hardly the only piece of evidence in any direction, it's not really a story about this one piece of evidence. But it's critical to root this stuff out, call it out, and address it head on, for the same reasons it's important to call out the corruption of any other process. You can't tolerate this stuff, or it gets worse. I would by the first to criticize anyone who published one of the (many) scientific publications that bolster my personal beliefs if they refused to share data with "critics". This is basic science.