I don't agree as each vehicle needs it's own individual circumstances considered before it's a clear cut yes or no to entitlement as a genuine Survivor..
While you've got some valid points to consider, an otherwise original ZL1 w/ replacement fenders or original Boss 429 car w/ a correct and admitted replacement engine could certainly be considered a Survivor if all else is deemed worthy?.
Here's Bloomington's base Survivor judging criteria...considering they're the ones who started and copyrighted the 'Survivor' term, it's worth reviewing!.
http://www.bloomingtongold.com/judging_criteria.pdf
I feel it's a good thing they've left enough room for cars w/ some issues to still attain Survivor status as otherwise these cars would be restored and what originality they do or did have to offer would be lost..
~ Pete