The answer lies in a book called 'Taqwiat-ul-Iman' (Strengthening Faith), written in 1820s, by a famous Indian preacher, Shah Ismail Dehlvi.
After key leaders of the Wahhabi umbrella in the form of Deoband, its missionary wing Tabligh Jamaat and Ahle-Hadis, a stream that is followed by Lashkar-e-Taiba in Pakistan, took an anti-yoga stand saying it was against the tenets of true Islam, it has been indeed heartening for patriotic Indians to see many Wahhabis, particularly students, doing yoga in cities like Ahmedabad. A Deobandi leader even performed yoga with Baba Ramdev at a public stage in Delhi recently. It only shows that apart from Sufi or Barelvi Muslims, who have openly supported yoga, there is a moderate section in Wahhabis too which is not opposed to yoga, howsoever small or big that might be.
Still, it is necessary to go into facts as to why the Wahhabis oppose yoga. A look into the Wahhabi history shows that the anti-yoga stand is rooted in a book called Taqwiat-ul-Iman (Strengthening Faith) written in 1820s by a famous Indian preacher, Shah Ismail Dehlvi, who died fighting against the Sikhs in the battle of Balakot (now in Pakistan-occupied Kashmir) in 1831 along with his preceptor, Syed Ahmed Barelvi, labelled as Syed Ahmed Wahhabi by the Britishers at that time.