@Caits You are right, and this is how a prefer to write my characters. I do not like to deal as much in absolutes because I feel that is OP and leaves less room for flexibility. Just my opinion. We are also dealing with a universe where cosmic beings are able to destroy whole universes and rewrite reality at a whim. There are greater telepaths both Marvel and DC (
Xavier is 16th on this list and Emma is 22nd). So one would need to be at that level to be entirely immune IMO. There's also the matter of, absolute immunity would have greatly hindered her communication with her people, since they don't use verbal speech.
Anyhow, being in an upper class on her planet she would have had many of the higher tier telepaths around her. What's more she would have had hundreds to thousands of people that could potentially read her mind at once, all of which she mush rebuff simultaneously (nevermind millions if there was a special event that brought everyone together). The idea is that it is a natural thing for her to do and she can do it in her sleep. Her telepathy has a primary focus on resistance to prevent everyone around her from reading her mind. That's how I wrote her and her race.
However I am open to creative ways of usurping the resistance, I just don't think it would be as simple as skimming the surface. Barca is going to actually have to try and Estella would know he's trying and then try herself. It would just be a matter of if Barca is able to output more than thousands on natural telepaths to break into someone's mind that has had hundreds of generations to build it up resistance.
Also doesn't he need something to aspire to or have out of his reach? That would make two people he's encountered an enigma because he can't just walk all over their minds like he's used to.
And if you would like to argue semantics, Barca knows zero about Estella's race because she's the first to ever be encountered. There is no detailed record of her, how her brain functions, or any of that. At the very least there wouldn't have been when he was born. Because "all the knowledge in the world" is singular and would likely be the planet he was born on.