I believe what they are saying is that "He was discussing targeted assassinations. One doesn't "target" an innocent person" seems to imply a logical fallacy:

(1) Person X is targeted -> (2) innocent people don't get targeted -> (3) therefore person X must not be innocent

The problem is that (2) contains too many bad assumptions: that the person doing the targeting is benevolent, that there's sufficient due process to ensure the targeter is correct, that there's a universally agreed definition of "innocent", etc.

History has proven that innocent people DO get targeted, so even from a common sense perspective your statement doesn't withstand scrutiny.