Salaam alaykum wa rahmatullah,
Hearing them curse Umar (ra) so much, I wonder how they fail to blame their own "infallibles" (ra) starting with Imam Ali (ra).
Quoting Alqatrah.net - "A Website dedicated to the views and lectures of Sheikh Yasser al-Habib" - it says regarding the (non)attack on Fatima (ra) by Umar (ra), "At this point Our Lady Fatima al-Zahra (Peace and Blessings upon Her) cried out. Imam Ali Ibn Abi Talib (Peace and Blessings upon Them) heard her voice and rushed to her aid. He took Omar, threw him to the ground, stepped on his nose and was about to kill him but for the fact of his thinking back to the order given to Him by the Prophet (Allah's Peace and Blessings upon Him and His pure Family)
to be patient in the face of tyranny so long as his supporters were too few in number." source:
http://www.alqatrah.net/en/al30Then why didn't Imam Ali (ra) do anything when he was the Caliph and in command of the army? He did not reclaim Fadak, he did not change the ways of the First Three (ra), he did not even criticize - let alone curse - them!
Imam Hassan (ra), same! When he became the Caliph, forget about reviving Islam (as Shias claim is the duty of the Imam), he entrusted Muawiya with the affairs of the Ummah and handed him his own "Divinely Ordained Right".