[25b top] Rivta: A self-incriminating testimony does not disqualify the actual witness himself, rather a relative is not even considered an acceptable witness in the first place; he does not even get the title of “witness” [and thus would not ruin other peoples’ testimony if part of a larger group]. Therefore, it is the testimony itself that is not “qualified” to be accepted because it does not come from a valid source.
D-E-ep Thoughts: It is often challenging to separate people from their speech/actions. We may term actions as unacceptable or evil, but we must not label people themselves. Each Jew has a divine spark within the body and we must help let that light shine through. We are obligated to help people turn around and repent from their ways (if they are willing), and bring the world to higher levels.