Where is your proof that terrorists have been deterred? Or are you assuming this is something which cannot be disproved? Your argument invokes a logical fallacy, particularly an appeal to fear and an appeal to consequences.
Which of course doesn't mean that he's wrong.
That's not to say that making a claim of fallacy isn't an indirect attack on the conclusion, especially when the only arguments supporting that conclusion are fallacious...
Wrong is the wrong word :)
What you're looking for is "invalid". An argument is valid if and only if the conclusion follows from the premises. In other words, if the premises are true then it cannot be the case that the conclusion is false. Since a logical fallacy adds nothing to an argument, the conclusion does not follow from the premise. Since the conclusion can therefore be false, even if the logical fallacy is true, the argument is labeled invalid.
Just for completeness... A more strict standard is soundness. An argument is sound if and only if the argument is valid and the premises are true. If an argument is sound, then the conclusion is necessarily true. Obviously, the argument invoking a logical fallacy as its premise is unsound because it is invalid.
It is also perfectly possible for the conclusion to be true even though the argument itself is invalid and unsound.
If you still would like to apply the label "wrong" to it, then I'd say, "The argument is wrong, even though your conclusion happens to be true."
(Note: I can't see the post that started all of this off as it has been deleted, so I'm not making any comment on the truthiness of his/her conclusion)
Indeed even if we have
A → B, A ⊢ B and can show that the initial premise is false (which reduces then to the above) we still can't say that the assertion of B [being true] is incorrect only that the logic is unsound.
In traditional style:
All men are Greek, Aristotle is a man ∴ Aristotle is Greek
Despite the premise being provably false (under ordinary interpretation), thus the argument being unsound, the truth of the conclusion is nonetheless still possible and indeed in this case there has been an Aristotle that is/was Greek.
Bringing it back to the current question the ancestor comment claimed something along the lines of (hard to check because it's deleted and in any case I'm paraphrasing):
Terrorists are deterred by airport security checks, TSA provide such security checks ∴ terrorists were deterred
Despite the premise being unclear and thus the logic lacking in rigour nonetheless it is still possible that indeed terrorists were deterred by the TSA.