What is there in the wording of the card that would lead you to believe you can kill all five? I'm assuming maybe this is a translation issue? Because the English version is very clear. You can only destroy two...
To your point, I agree that this is probably a translation issue. My thought is that it may be being interpreted as "Destroy [all units that are] up to 2 health worth of [
units of] your choice in the system". The card is also clear to me, but this is also my native language.