P: Complying with the new safety regulations is useless.
P's Argument
Complying with the new regulations is useless since, had they been in effect, they wouldn't have prevented last year's lab fire, nor do they address its underlying causes.
Q's Response
If the regulations can potentially prevent money from being wasted, then they're useful. And the new safety regulations will prevent some accidents, which would prevent money from being wasted.
Evaluate
Q is attempting to undermined P's conclusion but isn't disputing P's evidence. Nothing Q said is suggesting that the new safety regulations would have prevented last year's fire or would address its underlying causes.
Q seems to implicitly accept those ideas, but they bring up new considerations that argue against P's conclusion.
Q's evidence cites a principle "any regs that prevent wasted money are useful" and then shows how the new regulations satisfy the trigger of that principle.
Goal
Look for something like, .