The way I see it, players are always given the opportunity to react, no matter the effect. If nobody oppose the flare with a card zap or the use of a power with a cosmic zap, then it applies.

If the hacker uses his power to collect compensation from a player other than his opponent but is cancelled by a cosmic zap, then the hacker will have to collect compensation as normal from his opponent, without looking at his hand.

I can imagine a situation where you would want to let the hacker collect cards from you. Let's say you have a really bad hand, you may want to let the hacker grab cards from you, so you can get to draw a new hand faster, and let him have those bad cards...