Walden was in an ugly spot. Of course he didn't want Andromeda Black in his house. Katharina had drawn up the invitation list without consulting with him thereby putting him in a position where he had to defend her actions. Actions he found indefensible. No, Walden did not appreciate this at all.
"Like you said, Lucius, it is my son's birthday party. The people invited are invited for him. This is about Benjamin and children his age." Walden was having a hard time swallowing this shit himself, so with his one free hand he poured himself a drink hoping that would help wash the lump of bitter anger down.