Yeah, I wouldn't use BJJ in a streetfight unless I had to (like someone took me down), I'd want to keep it on the feet. Mobility is key when there are no rules and any bystander could turn out to be someone looking for the right moment to clock you in the back of the head.
His helmet was stifling, it narrowed his vision. And he must see far. His shield was heavy. It threw him off balance. And his target is far away.