It means they may have some critical thinking skills, not necessarily that they do.
It seem like you stated that you can have some critical thinking but not all of it. Not sure I understand that under the definition of critical thinking. Bolds mine.
statement by Michael Scriven & Richard Paul, presented at the 8th Annual International Conference on Critical Thinking and Education Reform, Summer 1987.
Critical thinking is the intellectually disciplined process of actively and skillfully conceptualizing, applying, analyzing, synthesizing, and/or evaluating information gathered from, or generated by, observation, experience, reflection, reasoning, or communication, as a guide to belief and action. In its exemplary form, it is based on universal intellectual values that transcend subject matter divisions: clarity, accuracy, precision, consistency, relevance, sound evidence, good reasons, depth, breadth, and fairness.
As you can see, critical thinking has more in common with a computer CPU than it does with the amount of knowledge that you hold. In database terms we name this "garbage in-garbage out". A computer is not any better than the information it holds. If you provide the right information it can process it and give a good outcome but you can not fault the CPU if the information isn't there. This is why you will get a bad response if you generalize 'lack of critical thinking' under something that could be defined as 'ignorance'. You are pretty much telling someone that they don't have a brain.
That not responding in such cases rests credibility to your views. Is a matter of honor, wether you are right or wrong. But that is fine, you don't have to. You owe the answer, not to me, but to your ideals.