LOL...who are "Dalit" Muslims ? I thought there was no caste system in Islam...
I think what he meant was that Dalits are seen as Untouchable by Hindus not by Muslims.
For your surpise i must tell you that there are also Dalit Sikhs, yes :).
One of the biggest reasons that many people are leaving Hinduism and converted and still daily (thousands of Hindus) to Islam, Christianity and Sikhism is because of the fact they want to come out of the cast. But even when they are converterd they have a ladder to climb and in India to climb a ladder is like climbing Mound Everest with bare feet.