In my opinion, thinks like this just become things a client can obsess over and punish themselves as a sort of punitive indulgence. It is not wrong to look at publicly available material on anyone. People often seem to be curious about their therapist (remember therapists are who set the game up so that they are mysteries), therapists know or should know this and take whatever precautions to ensure material they do not want to be public, out of the public realm. Students look me up, drive past my house, read things I have written and so forth. So long as they are not showing up on my doorstep - It just does not bother me. Any therapist who gets angry over being googled needs to find their own therapist and get a grip on themselves. Frankly I would think a therapist who got angry over that is really angry at themselves for failing to keep personal stuff off the internet if it is something they don't want clients to know or see.
I don't think there is anything to feel guilty over and I don't think confession is necessary or even good - who is the therapist/what would give them the power to absolve a client?