The author of this article from The New Yorker believes that viewers have had enough of TV characters with questionable morals. Jean-Luc Picard is not such a man. Maybe this is why Trekkies are excited to see his return. We love the character and his unambiguous sense of right and wrong.
Even though Patrick Stewart has expressed his personal opinions on several political issues recently, CBS has not stated officially that Star Trek: Picard has a thematic connection to Brexit or any other current political topic.
The article is here.