I think that completely misses the point of Amok Time.
There is no reason to assume T'Pring didn't want Spock because he wasn't her type - it's clear the issue is Spock's lifestyle leaving her completely alone all the time, and the SNW episodes we've seen make it adundantly clear that their relationship does have actual sparks in it, regardless. She clearly likes him a lot.
And there is no reason whatsoever why Stonn should be someone that Spock can't possibly defeat physically. T'Pring didn't choose Stonn because he could beat Spock in a fight. She just liked him and he chose to be there for her, which is something Spock chose not to do. And given that Spock is her type, it makes way more sense for Stonn to be physically similar to Spock than for him to be completely different in every way.