Mutual funds have bought them showing that they are like bonds. But they are not, and everyone knew that and no one assumed there will be a PONV event.
Btw, there was a near-default recently on United Bank I think, but RBI or Govt forced them to buyback the bonds.
That was unnecessary mollycoddling (these are sophisticated investors who can read).
Meanwhile, if you're willing to sell HDFC Bank AT1 bonds at a 15% yield, I might consider taking them off your hands.