Actually, her ordinary is the archbishop of San Francisco, which ought to free Archbishop of any scruples in co-signing that letter.
Wuerl is not Pelosi's "home" bishop, but rather is the bishop over DC. That said, he still should refuse her, but it's really up to her SF bishop re whether she's a "Catholic in good standing" or not.
Thanks for correcting me. I knew that Pelosi had a bishop "back home", and a different one giving her communion in DC, but I had mistakenly accorded Wuerl with being the bishop "back home". I was remembering the roles exactly as you describe them, but had Wuerl in the wrong location.