With regards to your specific query, firstly the claim that the Hadith which mentions Raf-ul-yadayn (raising of the hands) before and after ruku only is Mutawaatir is questionable. (see I’elaa-us-sunan vol.3 pg.80)
Secondly, the Hanafi are not the sole holders of the view that Raf-ul-yadayn should not be done. Instead, thee are other eminent Mujtahideen also who are of the same view, i.e. Imaam Sufyaan al-Thawri (ra), Imaam Maalik (ra) – according to one view – and other Mujtahideen of Kufah, etc. This was also the practice of the illustrious khulafaa-e-raashiden; Sayyiduna Umar ibn al-Khattaab [Radhiallaahu anhu], Sayyiduna Aliy ibn Abi-Talib [Radhiallahu anhu]. (see athaarus-sunan pg.134-140; I’elaa-us-sunan vol.3 pgs.56-90; Musannaf ibn Abi Shaybah vol.1 ph.236-237)
Some of the proofs that support the view of not raising the hands, i.e. the view of Imaam Abu Hanifa [ra] and others, are the following:
1. Imaams Abu Dawud, al-Tirmidhi, Nasaaie (RA) have recorded in their Sunans that once Sayyiduna Abdullah ibn Mas’ood (Radhiallaahu Anhu) said, ‘Should I not show you the Salaat of Rasulullah (Sallallaahu Alayhi Wasallam)?’ He, then stood up and he raised his hands for the first time (for Takbir-e-Tahrima). Thereafter, he did not raise his hands. (Sunan Abu Dawud pg.109; Sunan al-Tirmidhi pg.58; Sunan Nasaaie vol.1 pg.158). The narration has been classified as authentic by Imaam Nimawi [ra]. (Aathaar-us-sunan pg.133)
2. Sayyiduna Barraa ibn Aazib [Radhiallaahu anhu] reported that when Rasulullah [Sallallahu alayhi Wasallam] used to commence his Salaat, he would raise his hands upto close to his ears and thereafter he would not repeat this act (of raising the hands) in Salaat.’ (Tahaawi vol.1 pg.132; Sunan Abi Dawud Hadith109). Allaamah Muhammad Yusuf al-Binnori [ra] has stated that this Hadith is an authentic argument (see Ma’arifus-sunan vol.2 pg.493)
3. Saalim [Radhiallaahu anhu] reports from Sayyiduna Abdullah ibn Umar [Radhiallaahu anhu] that Rasulullah [Sallallahu Alayhi Wasallam] used to raise his hands at the beginning of the Salaat and he would not repeat it. (al-Khilaafiyyaat of Imaam al-Bayhaqi)
Among the Sahaaba [Radhiallaahu anhum] who did not practice on Raf-ul-yadayn are: Sayyiduna Umar ibn al-Khattaab [Radhiallaahu anhu], Sayyiduna Aliy [Radhiallaahu anhu], Sayyiduna Abdullah ibn Mas’ood [Radhiallahu anhu], Sayyiduna Abu Hurayra [Radhiallaahu anhu], Sayyiduna Barraa ibn Aazib [Radhiallaahu anhu] Sayyiduna Ka’ab ibn Hujrah [Radhiallaahu anhu]. (Ma’arifus-sunan vol.2 pg.464)
Those Mujtahideen that are of the opinion that Raf-ul-yadayn should only be practiced at the beginning of Salaat have further argued that they accept the Ahadith that prove Raf-ul-yadayn at the various postures of Salaat to be authentic. However, those have been abrogated by other Ahaadith, the act of Raf-ul-yadayn remained the practice of Rasulullah [Sallallaahu Alayhi Wasallam] for a while, but later on it was gradually abandoned. (I’elaa-us-sunan vol.3 pg.79)
There are various technical proofs that substantiate this claim. We chose not to mention them for fear of causing confusion on the readers that are not fully equipped with the knowledge of Usoolul Fiqh. However, if you are interest in these finer details, kindly refer to I’elaa-us-sunan vol.3 pgs.56-90, Athaarus-sunan, Ma’arifus sunan vol.2 pg.451-501.
and Allah Ta’ala Knows Best
Moulana Muhammad ibn Moulana Haroon Abasoomar