GP said "long-term climate trend" and then mentioned centuries. Yes, an especially large eruption can influence things for a year or two. But then the effect settles out.
Well this flooding is occurring 8 months after the eruption mentioned so it seems a reasonable question to ask.
Ah, fair. A single eruption will not perturb the long-term trend, but we're discussing the short-term incident in Pakistan, and a single eruption can have notable short-term impact. (I don't know anything about whether the specific eruption in question could have any impact on this specific crisis in Pakistan.)