Principle of charity: "Denial of existence" is to taken as meaning "Don't think about, don't care about, don't act based on, don't know how many there were" and not "When explicitly asked if drone strikes have victims, say 'no'."
There is already a word for "don't think about, don't care about, don't act based on, don't know how many there were". That word is "disregarding", which is used in the original quote. It then adds, a fortiori, "and in many cases outright denying the existence of victims of drone strikes". In that context, it cannot mean anything but "explicitly say that there are no victims", and in addition, that this has actually happened in "many" cases.
Another month has passed and here is a new rationality quotes thread. The usual rules are: