Well, I'm basing that off of him having an attack called "Megaton Punch", which puts him literally at the exact bare minimum level of Low 7-B, or also the exact highest level of High 7-C. Even Hero Hunter Garou who is High 7-C+ would probably stomp him. Even if his AP would be a bit lower, the massive advantage in every other regard, especially skill, would be too much for Hercule to keep up with. If he went against Tank-Top Master though, it could be a fight, but he isn't Low 7-B, just High 7-C.
Also Hercule would still get blitzed by them. Low 7-B wouldn't change his Subsonic speed, unless we're using speed equalized.