Soay tups are a bit different. In their natural habitat ie living on an island without human supervision, numbers of males to females are roughly equal. Tups have a rut like deer and fight to defend their harem of females. So fighting and defending territory is a natural and essential part of a successful tups life. Soays have not lived in a domestic environment for many generations so their behaviour has not been much modified. Most other breeds have been domesticated for many generations, even centuries, being given a harem they don't have to fight for or defend, so they are less aggressive than Soays.
Small though they are, Soay tups don't seem to realise they are the smallest chaps around and they are completely fearless in a fight - usually started by them.
Presumably as part of their environment, a Soay tup will see you as something else to beat up. We have had some ok Soay tups and some aggressive wee devils over the years, but mostly they have restricted their aggression to other tups.