Well, I have six Chihuahuas and the only dogs that have ever been nasty to them (as in wanting to attack them) are Jack Russells (several times) and a Chow (on one occasion). Thankfully none of the attacks were any more serious than a bite which didn't cause any major problem (apart from scaring the life out of my dogs - lol). I find SBT's, GSD's and big/powerful dogs, generally, to be fine with my dogs, even to the point of ignoring them.

I would also say that the Kennels seem to have been majorly negligent. My Daughter worked at a Kennels in the Summer and all dogs were walked in a field separately, on lead at all times. Any dogs that were a slight worry with other dogs/workers, were kept in kennels over the other side of the field to minimise any possibility of the dog being able to harm anyone. What the Kennel Owners did to cover up the "accident" was despicable - they should have lost their License on that point alone! Disgusting!

I personally like SBT's very much. Have never met a nasty/aggressive one and there are several in the family. If I ever went for a bigger dog, it would be an SBT, for sure!

we don't know anything about those dogs so we can't really say anything like that, they may have been rescues and/or attacked previously we don't know why they are aggressive

It is totally sicking really!
But I suppose most dogs are just as capable of doing something like that not just staffies ir staffy x's.
I blame the owners.....MORONS!