Historically, the Apparel Events' completion bonus reward has been an exclusive vanity item; excluded from the events' items subsequent transfer to the Standard Apparel cache pool. In short, no. However, you've confused two items, so, yes and no. You will be able to get the Black Balaclava later, but not directly via purchase.
The Black Balaclava is NOT the event's bonus reward. The Black Balaclava is the bonus reward for completing the event's four outfits (Specialist, Bastion, Mechanic, Enforcer). This information is readily available when you click in the in-game menus under Store > Apparel > Outfits > Last Resort. Highlighting the outfit event (ie. Last Resort) displays the outfits' completion reward. Highlighting an outfit therein displays any respective rewards for competing said outfit.
The Last Resort Apparel Event's bonus reward is the Rikers Bandana. This information is available only while the event is active, by highlighting the respective Apparel Event Cache and selecting Contents. You'll find it at the top of your screen under Completion Reward.
If you want the Rikers Bandana, I suggest you complete the NY campaign and get your SHD status before the event concludes.