That tweet was in reference to Jon Sopel's report on this morning's Today, and I agree with Jane that it betrays a social liberal bias on the part of the BBC reporter:
BBC Newsreader: President Trump has been handed the opportunity to shift America's highest court further to the right with the retirement of one of its judges. Justice Anthony Kennedy is stepping down from the Supreme Court after three decades in the role. Viewed as a moderate conservative he has advanced gay rights and opposed attempts to restrict abortions. Here's our North America editor Jon Sopel.
Jon Sopel: For over a decade Justice Anthony Kennedy has been the key swing vote on the Supreme Court and in some ways its conscience. He came down in favour of same-sex marriage, allowing that measure to pass 5 to 4, and was decisive in resisting efforts to tighten abortion laws. But with his departure Donald Trump is presented with an opportunity to appoint another conservative to the bench, something he's committed to do. With mid-term elections in November, which theoretically could lead to Democrats taking charge of any confirmation hearing, there is an impetus to get this done as quickly as possible. Presidents may only be able to serve eight years; a Supreme Court justice is for life. And conservatives are eyeing an opportunity to change US social policy for a generation.
Of course, the use of the word "moderate" in the introduction there is also something of a value judgment.