The material is wrong. Superman has moved the earth out of the sun's orbit. to do this, you'd have to be able to move 1/1000 of the object's weight. earth weighs a little under 6.6 sextillion tons (6,600,000,000,000,000,000,000). so that means he is strong enough to move quintillion tons.

I never heard anything about him being limited to 100 tons.

source: www.screwattack.com/shows/originals/death-battle/death-battle-preview-superman