My question is, could residual sanitizer kill enough of the yeast so it doesn't reach it's maximum fermentation?
Probably not. Fermentability is set by the mash, and influenced to some extent by the yeast's genetics. Killing off, say, 50% of the culture, or even 99%, wouldn't impact the remaining cells' ability to ferment down to that inherent limit, it would just increase the amount of time needed.
More practically, having enough sanitizer left to kill off an appreciable number of yeast once diluted by the wort would have flavor impacts that far outweigh the microbiological concerns. The extreme case would be PAA due to its oxidation potential.