The best stuntman to portray Matt Damon's character fighting a 7 foot tall monster would be a short a stuntman as possible to make the "Monster" Stunt man look even bigger. Best person for the job happens to be a 5'4" woman.
She is actually less than 5 feet tall.
A thread about this has been zotted twice today; and I don’t think people are understanding the issue.
They needed a very small person for the photographic effect they were after, and Dalton was very short and had a physique that fit.
This is very different from casting a Black woman as Helen. It would have been very hard to find a male under 5 feet tall for their purposes.