The choice of weapon is quite open for Tachanka as her skill is a weapon too. Even if you go down, your team can use your skills. Although Tachanka was largely considered a 'meme-choice' in Siege, he is actually incredibly useful in Rainbow Six: Extraction with his ability to eliminate large amounts of archeans faster than any other operator in the game.

Perhaps Rainbow Six: Siege's most infamous operator, Tachanka is back in the extraction zone to take out some archaics with some classic weapons.