The majority of 'killer dairy bulls' disposition is due to the fact they were bottle/pale raised by humans. They imprint on humans and begin to think of humans as their natural competition for reproductive success and will be incredibly aggressive towards people, especially men, when being handled as mature animals.
Same goes for most species actually- most dangerous animal to a person is a bottle raised, intact male.
If your gomer was raised on it's mother, or on a foster cow in your beef herd, (that's a whole other level of biosecurity questions...!) a dairy bulls attitude will likely be no different than your average beef bull. Obviously be cautious of any bull, none of them should be trusted, but if he wasn't bottle/pale fed then attitude likely wouldn't be a huge issue.