Angel's failure to refuse outright was, in truth, good news for Nuka.
Given Shava's exalted status, if she truly disagreed, she would definitely have refused without hesitation. Since she had left a little room for maneuver, it at least meant there was still a strong possibility that Shava was inclined to attend the banquet.
As for how to turn that "inclination" into reality, Nuka felt that this might be the test Shava had given him.
Perhaps if he performed well enough, Shava would nod and agree.
But how should he perform, and where should he begin? Naturally, with the banquet at hand.
At that thought, Nuka's tiny eyes narrowed into crescent slits as he said to Angel, "Lord Shava is right. It's too early to bring up plans now; changes could come at any moment."
Angel: ... Had I said that?
"Fine, then we'll see how things stand when the time comes." Nuka nodded to Angel, then raised his glass of crimson liquid in a distant toast.
Angel had no idea what Nuka was thinking, but according to table etiquette, he also picked up his glass and returned the gesture. Naturally, the wine he drank did not enter his stomach. Instead, wrapped in Nightmare Illusion aura, it was drawn into the Nightmare Domain.
Throughout the rest of the banquet, Nuka did not mention asking Angel for help again, nor did he raise any questions that would leave Angel unable to save face or answer. Instead, whenever Angel asked something, Nuka answered every question.
He was even exceedingly eager to fulfill Angel's requests. Nuka had learned from the Book of Madness that Angel seemed interested in Message Mushrooms, so he immediately dispatched a little mouse to arrange for all the Message Mushrooms in the mushroom garden to be brought to Angel.