Harry's reasoning regarding Narcissa's lie is faulty

[curlyhornedsnorkack]

No: HPFGUIDX 178047

When Narcissa lied to Voldemort that Harry was dead, Harry reasoned 
that she lied because she wouldn't be allowed into the Castle  
quickly if she wasn't going in as part of a victory march.  Perhaps 
all the stress of dying and coming back muddled Harry's reasoning. 
The death eaters would have had no trouble finishing Harry off there 
and then if she had said he was alive. If wands didn't work, at least 
one of them had a knife.

It makes more sense that Narcissa lied to end Voldemort's reign. She 
had nothing to gain from having Voldemort alive. She and her husband 
were no longer valued death eaters. They were terrified. Voldemort 
was using their property and their son as he pleased. Narcissa would 
have heard Harry referred to as "the chosen one" to stop Voldemort, 
and when she heard the miracle of his heartbeat, she would have known 
it to be true. She risked her life, and her husband's and son's 
lives, in the hope that Harry really could kill Voldemort and end 
their misery. 

I have been away from this site for a long while, and while I did 
search to see whether this was mentioned, I could have missed it. 
Snorkacks have very long hibernations. Sorry in advance.

-Snorky