This is actually a pretty safe house...
But seriously, even taking me out of the equation, how dumb do you have to be to try and act threatening to someone when they have a very large dog with them? Def
Not everybody is nervous around dogs... they might have a bigger one. That said, the earlier post was right: pack mentality with something to prove.
The sad fact is that it's evolution. Look at James Dean- he was the baddest of the bad in his day. Now look at the kids in almost every neighborhood- they make ol'Jimmy look like a choir boy.