Please Bilal don't try to justify it.
No, I'm not trying to justify it. It was a wrong & poorly structured sentenced. It was extremely poorly thought out, & offensive.
But if you really want to know a bit more about why that might have been said, you have to understand that Islam did a lot to mitigate & eradicate slavery, & the caste system is a bit opposite to that.
In addition to that, I have to admit something, & I think Pakistanis would agree with me. Muslims had a fear that they would be dominated by the Hindus, & after ruling the Indian subcontinent for over 700 years, & even though Mangal Pandey was instrumental in the Indian Mutiny 1857, it was the Muslims that had to face the brunt of it from the British over the coming decades.
Post-1857 lead to a pensive approach from Indian Muslims (who were distraught for facing the consequences of 1857), which resulted in two different streamlined approaches. The first one was the hardline Deobandi approach (the Muslims who felt they had lost their status because they deviated from Islam), the other was the secular approach (Aligarh formed by Sir Syed Ahmed Khan, who felt Muslims needed to adapt with time & changes to prosper). But it was felt amongst Muslims that they would be remain downtrodden, & dominated by the Hindus in the eyes of the British.
Let me tell you something very interesting. All Pakistani books shower praise on Sir Syed Ahmed Khan's secular approach, & the Deobandi radicals were condemned. They were especially condemned in Pakistani books for opposing the formation of Pakistan.