Oh yeah, I forgot about his closeness with Donna! But, the type of person Donna was (Is? She didn't die did she?) she wouldn't want Paul to be out to avenge Ringo on her behalf.
God, that was so long ago! Aha
Maybe something about Lyn would make sense with Carla Bonner saying she going to try and get some family and friends back. But I just don't see anything justifying Paul's actions. Not saying that's what you were implying, but he just...ugh, frustrates me so much for a fictional character Especially because he has shown so many times that he does have a true human side to him.