Shia cleric distorts the verse of Quran - best nation or best Imams?

[MuslimK]

بسم الله الرحمن الرحیم

So this guys says (and quotes narration of their Imam) that a man read this verse before their infallible Imam:

كُنتُمْ خَيْرَ أُمَّةٍ أُخْرِجَتْ لِلنَّاسِ
You are the best Ummah produced [as an example] for mankind. (al-i-Imran verse 110)

but Imam Sadiq tells him: "the best Ummah (nation) kill Husayn?", the questioner asks "how was it then revealed oh son of Rasoullallah?", the Imam reads the 'Original' verse and says it is actually "You are the Best Imams (Aimah) produced for mankind" and they are us.

See the Shia sources:
Tafsir Qummi vol.1, pg.10
Tafsir Ayyashi vol.1, pg.195
Tafsir Majma'a al-bayan of Tabrasi vol.2, pg.358

and many other.

Scan from Tafsir Qummi in the end:

Notice the word of the Ali bin Ibrahim Qummi, the author: "As for what opposes what was originally revealed by Allah, it is {You were the best nation}…] then quotes the opinion of Jafar Sadiq who reads the 'original verse' that was revealed by Allah....

Arabic text:
واما ما هو كان على خلاف ما انزل الله فهو قوله " كنتم خير أمة أخرجت للناس تأمرون بالمعروف وتنهون عن المنكر وتؤمنون بالله " فقال أبو عبد الله ع لقاري هذه الآية " خير أمة " يقتلون أمير المؤمنين والحسن والحسين بن علي ع ؟ فقيل له وكيف نزلت يا بن رسول الله ؟ فقال إنما نزلت " كنتم خير أئمة أخرجت للناس " الا ترى مدح الله لهم في آخر الآية " تأمرون بالمعروف وتنهون عن المنكر وتؤمنون بالله "