Yep. He’s a fatuous poser. Don portends something different coming - I think of it as the groundwork being laid for The Sixties - but in the context of the show, he’s earned the right to break the roles, by having invested so deeply in them for so long.
You nailed it. And the idea that an adopted child is a “reject” or less loveable than a biological child is particularly hurtful to my boyfriend, who still feels that his father didn’t love him as much as if he had been biologically related. Now, if Pete were a real person, I’d feel obliged to consider that he does have some good qualities (presumably, though I can’t think of any at the moment) and that Trudy handled her end poorly. But as he’s just a fictional character, I’m happy to write him off completely.