Why must the circumnavigation of UY Scuti be treated as a purely geometric calculation of its photosphere perimeter?

Answer

A stable, Earth-like object of this size is physically implausible due to self-gravity

Due to its immense size, a stable structure resembling an Earth-like object would be physically implausible because of self-gravity, requiring hypothetical exotic materials or a hollow structure.

Why must the circumnavigation of UY Scuti be treated as a purely geometric calculation of its photosphere perimeter?
astronomystarUY ScutiCircumnavigation