Why should Jake need to give anyone evidence of some of his relatives' and friends' bigotry?  It's his opinion that they are bigoted, and he is re-evaluating his relationship with them.  Unless you know Jake personally, and/or know the people to whom he refers, why would it matter to you?  Jake is not telling you, or anyone else, not to interact with them.  
Yes, if I were to accuse a particular person of bigotry, I should have good reasons.  If it were a public person, or someone whom you knew or knew about, then I should be willing to give my reasons.  But if I mention to someone that I dislike some of my cousins, because I consider them to be bigoted, and don't name the cousins or don't say anything that would identify them, I don't think that it's necessary to explain to others what it is that they do that is bigoted.  
Your last sentence is a non sequitur.