Even if it did human - Vulcan interbreeding would only work if such unions were naturally fertile and produced fertile offspring. Until and unless canon states otherwise to me Spock was the result of painstaking genetic engineering and is infertile.
Since when was it said Spock was infertile?
Yeh I reckons he's very fertile
B'Elanna was 'fertile'. K'Ehlyrr was 'fertile'. Both conceived kids without medical intervention. Yeh I know that was Human-Klingon but why would that be more/less believable the Human/Vulcan.