It is perfectly reasonable to make a partisan attack in this case
No, partisan attacks are by definition NEVER reasonable.
Of course they are. They serve the purpose of undermining one's enemy. But in this case jfern is also making a valid criticism, partisanship aside.
I never said partisan attacks didn't have a purpose, I said they were always unreasonable. Even IF jfern has a valid criticism(which is different from an attack), being partisan is unreasonable because it makes the assumption that the other side is always wrong without considering the facts.