A sane person, noting that assumptions about proportions and scaling lead to questionable answers, first thinks about adjusting assumptions.
But you, who are clever enough to equate the proportions of your seven foot fossil with that of a teratorn, are a world class expert on assumptions.
Regardless of the properly done math, they fudged their answers with no good reason to suspect that the Square Cube Law was in any way wrong. Nor do they have any evidence that the assumptions about body density is somehow different for larger sauropods than for smaller ones. They merely adjust downward until they were more comfortable with the answers... and that is NOT good science. That is sweeping the data under the rug and ignoring something that doesn't fit their preconceived notions.
You, on the other hand, choose to attack my sanity. JS, even their doctored results are far beyond the theoretical maximum for animals to walk on land... far beyond. What do you think would be an acceptable weight for a 120 foot dinosaur? And what would it be made of? Helium?