Is a criminal plea in a court of law not suitable justification to disbar a lawyer? We're not talking about a criminal plea involving actions not directly related to the law such as a DWI. We're talking about crimes directly related to acting as a lawyer and interacting with a judge and a court.

I don't believe that last bit is entirely correct. My understanding is that her guilty plea in GA was related to efforts to interfere with election duties (ie. attempts to gain unauthorized access to elections equipment and records), and did not involve any of her interaction with judges or courts:

apnews.com - Sidney powell plea deal georgia election indictment

I don't practice in Texas, but as a general matter you're not likely to get disbarred for committing misdemeanors, unless those misdemeanors were committed against the state's courts or your clients. And even then. Disbarment is a "death penalty" sanction for lawyers, and it's rarely imposed.

I couldn't find the appeals court ruling (though I didn't spend all that much time looking), but from context it does not appear that Powell's actions in the state courts of Texas were particularly egregious (which makes sense - Texas wasn't really a battleground for the 2020 election). And that the Bar's disciplinary action was based on her actions in Texas state courts. Taken together, it's not shocking that the courts found disbarment to be unsupported by the record - but again, without reading the opinion, it's hard to say whether there might have been anything else that the Bar sought to include).