It's probably part of the whole package. First, the family is not well off, and a brother getting his sister married is not the same as parents doing it, at least that is what Sam's father thinks.
Then there is the issue of morals--in the father's eyes, Aarti is of dubious morals for falling in love with a boy. Then Aditya comes across as a philanderer. And finally, his love child has a genetic condition, which Aarti might carry in her genes too. People are very sensitive about potential for genetic problems, and in many arranged marriages, will reject rishtas with families where there are huge medical or genetic issues.
It's possible that the autism came from Anuradha. We will never know till they decide whether to make Vidya's unborn kid 'normal' or not.
But in the meantime, Sam's father is awful, and I can't see anything good in him. Moneygrubbing, judgmental old meanie.
Mahika.