Absolutely. You have the right to see your opponents cards if you paid to see them (or if there were no bets and the hand went to a showdown and your opponent(s) mucked).

In this case, you would ask the dealer to see your opponents hand (if it wasn't shown already).

I'm not arguing with you there, nor did I ever say that wasn't the case.

The point is, the little old lady had every right to muck her hand and the hand was dead (even if she was all-in) when the hand hit the muck.