The Shia justify their belief of Taqiyah on the basis of Yaasir Ammar's action.

Answer

Their argument is fallacious. The relevant Qur'aanic verse allowing verbal denial of Imaan while concealing it in the heart as Hadhrat Ammaar (radhiyallahu anhu) had done under severe torture is never a basis for Shiah Taqiyah. Shiah's practise Taqiyah as a doctrine of great virtue. For them it is a doctrine of holy hypocrisy. Torture is not a condition for Taqiyah in Shi'ism. They will lie and deceive the Ahlus Sunnah without there being the slightest threat to them. Without any torture whatsoever, they practise Taqiyah on just any issue. For example, they will tell us that they believe in the same Qur'aan as we do while their official kitaabs of their greatest ayatollahs emphatically deny the authenticity of the Qur'aan Majeed. There is no basis in the Qur'aan and Sunnah for the Shiah doctrine of Taqiyah (Holy Hypocrisy).