2004 Ford Explorer Metal inside intake manifold

The motor in my explorer locked up. I took it to the dealer who dropped the oil pan and discovered metal shavings in the oil pan and bottom of motor and said the motor needed replaced. Remanufactured motor ordered from Ford and installed. The engine knocked so they had to order another one (no cost to me). So, onto my question. I get a call from the dealer saying that when the original motor locked up it shot metal shrapnel up into the intake and now I need a new intake at a cost of $400. Does this sound correct?

Thanks!

Update: dealer used a borescope and it seems there may be part of a valve embedded up inside the intake.