So? They'll just kill it. It's not like destroying planets is a big thing in DBZ. Veggie on earth could blow up the planet at a (and yes, I know, they're bullshit) power level of 18k. Frieda in his most suppressed form is at 530k and his family is right up there with him. Plus, there's quite a few people in their armies either at Veggies level or above him.