I think they don't have grounds because to call a claim crazy is to say that it differs from objective reality in a way that suggests a disconnection from a baseline view of that reality. So, like, it's not crazy to say that a home run traveled 420 ft when it actually traveled 400 ft, but to think that it traveled 750 ft suggests that you don't really get the physics of baseball (easy mistake for a non-fan, but one a fan would never make). But MTG's craziest claims are entirely plausible within the deeper worldview pushed by rightist media. It's just that most people who operate within that environment realize that it's a game, and MTG (like a lot of the audience) doesn't. So for GOP officials, talk show hosts, or columnists/bloggers to criticize her would imply revealing that they don't really believe the official rightist infotainment universe narrative. They can't do that without losing the audience.
There are crazy individuals on the left, but the culture isn't in a similar state. I think there are legitimate (and serious) criticisms that can be made of how Israel has conducted the conflict, and some nuts have kind of taken off from there to antisemitism or support for Hamas. There are also corners of the left that take a general view that whatever the U.S. does is bad (these are also the dipshits that tend to side with Russia in their invasion and China in various conflicts). But the mainstream left has no equivalent problem with calling them out. Within Democratic leadership, you have lots of big Israel defenders (too big, IMO). And generally there is vigorous intra-left debate going on (with no one in the mainstream taking the pro-Hamas/antisemitic position of some losers on Twitter). Compare that to how you have no one in Republican leadership willing to call out bullshit going around the right (leadership is continuing to push that Biden bribe stuff even after the key witness was found to be lying and all other evidence has fallen apart). The reason is that there isn't a cultural symmetry.
