I can't say that I have noticed a different guarding style depended on gender. I am unaware of any scientific study on the differences of guarding styles.

I have seen something on different styles based upon breed. But I'm not sure how much stock I put into that. I don't think there was enugh studying to come to a factual conclusion. But that s just my opinion.

In my dogs I have not witness a different guarding style. But I have grown to prefer females for guardians over male. Most people want a male. But when they ask me I will guide them to females as guardians. Sure males are bigger and often can be viewed as more intimidating. But a male might escape your property because a female is in heat nearby. Some males will ignore the stranger and stop guarding because a female is in heat. You don't have these types of issue with female dos. Either gender is more than capable of doing the work.